Exhibit 99.1

TRANSOCEAN LTD. REPORTS FOURTH QUARTER AND FULL YEAR 2012 RESULTS

·                  Fourth quarter 2012 revenues were $2.326 billion, compared with $2.431 billion in the third quarter 2012;

·                  Operating and maintenance expenses for the fourth quarter were $1.438 billion, compared with $1.321 billion in the third quarter 2012;

·                  Fourth quarter 2012 net income attributable to controlling interest was $456 million, which included $126 million of net favorable items.   This compares with the third quarter 2012 net loss attributable to controlling interest of $381 million, which included $887 million of net unfavorable items;

·                  Fourth quarter Annual Effective Tax Rate(1) from continuing operations was 7.8 percent, compared with 15.2 percent in the third quarter 2012;

·                  Fourth quarter net income attributable to controlling interest was $1.26 per diluted share.   After adjusting for net favorable items, adjusted earnings from continuing operations were $330 million, or $0.91 per diluted share;

·                  Cash flows from operating activities were $923 million in the fourth quarter, compared with $786 million in the third quarter 2012;

·                  Revenue efficiency(2) from continuing operations was 94.7 percent in the fourth quarter, compared with 94.9 percent, in the third quarter 2012.  Ultra-Deepwater revenue efficiency was 95.5 percent, compared with 95.9 percent in the prior quarter.  Total rig utilization(3) from continuing operations was 79 percent in the fourth quarter, compared with 80 percent in the third quarter 2012;

·                  New contracts associated with continuing operations totaling $2.0 billion were secured in the Fleet Status Report periods October 17, 2012 through February 14, 2013.  Backlog from continuing operations was $28.8 billion at February 14, 2013; and

·      During the fourth quarter of 2012, the company reclassified its drilling management services operations in the U.S. Gulf of Mexico to discontinued operations, reducing revenues and operating and maintenance expenses in the period by $51 million and $50 million, respectively.

ZUG, SWITZERLAND — Transocean Ltd. (NYSE: RIG) (SIX: RIGN) today reported net income attributable to controlling interest of $456 million, or $1.26 per diluted share, for the three months ended December 31, 2012.  Fourth quarter 2012 results included net favorable items of $126 million, or $0.35 per diluted share.  The results compare with a net loss attributable to controlling

interest of $6.2 billion, or $18.76 per diluted share, for the three months ended December 31, 2011.  Fourth quarter 2011 results included net unfavorable items of $6.3 billion, or $19.02 per diluted share.  The net unfavorable items in 2011 were primarily due to a loss on goodwill impairment of $5.2 billion, or $15.83 per diluted share, related to the contract drilling services reporting unit; and $1.0 billion, or $3.04 per diluted share, for estimated loss contingencies associated with the Macondo well incident.

Fourth quarter 2012 net favorable items, after tax, included the following:

·                  $101 million, or $0.28 per diluted share, associated with favorable discrete tax items, and

·                  $25 million, or $0.07 per diluted share, of income from discontinued operations primarily associated with the sale of the shallow water rigs.

After consideration of these net favorable items, adjusted earnings from continuing operations were $330 million, or $0.91 per diluted share.  A reconciliation of the non-GAAP adjusted net income and diluted earnings per share is included in the accompanying schedules.

Revenues from continuing operations for the three months ended December 31, 2012 were $2.326 billion, compared with revenues of $2.431 billion during the preceding three month period.  Contract drilling revenues decreased $35 million primarily due to the expected increase in out of service time, partly offset by higher average dayrates.  Revenue efficiency from continuing operations was 94.7 percent for the fourth quarter, compared with 94.9 percent in the third quarter 2012.  Other revenues decreased $70 million to $51 million for the fourth quarter 2012, compared with $121 million in the prior quarter, primarily due to lower drilling management services activity.

As expected, operating and maintenance expenses from continuing operations increased $117 million to $1.438 billion for the fourth quarter of 2012, compared with $1.321 billion for the prior quarter.  Contract drilling expenses increased $173 million primarily due to higher maintenance and shipyard costs associated with rigs undergoing surveys and other projects.  Costs associated primarily with the company’s drilling management services reporting unit decreased $56 million due to reduced activity.

General and administrative expenses were $65 million for the fourth quarter 2012, compared with $69 million in the previous quarter.

Transocean’s fourth quarter Effective Tax Rate(4) from continuing operations was (20.7) percent, compared with 16.5 percent in the third quarter 2012.  The decrease in the Effective Tax Rate was due to changes in estimates primarily related to settlements of prior years’ tax liabilities.  Transocean’s Annual Effective Tax Rate from continuing operations for the fourth quarter 2012 was 7.8 percent.  This compares with 15.2 percent for the prior quarter.  The decrease was primarily due to changes in the blend of income that is taxed based on gross revenues versus pre-tax income, the foreign exchange effect of the strengthened Norwegian krone versus the U.S. dollar, and rig movements between jurisdictions.  Fourth quarter 2012 income tax expense included a favorable adjustment of $37 million, or $0.10 per diluted share, required to decrease the 2012 Annual Effective Tax Rate to 17.8 percent from 20.5 percent for the nine months ended September 30, 2012.

Interest expense, net of amounts capitalized, was $180 million, unchanged from the prior quarter.  Capitalized interest for the fourth quarter was $18 million, compared with $12 million in the third quarter 2012.   Interest income decreased to $13 million in the fourth quarter, compared with $15 million in the third quarter 2012.

Cash flows from operating activities were $923 million for the fourth quarter, compared with $786 million for the third quarter 2012.  Capital expenditures from continuing operations were $657 million for the fourth quarter, compared with $201 million in the third quarter of 2012.

Full Year 2012

For the year ended December 31, 2012, net loss attributable to controlling interest totaled $219 million, or $0.62 per diluted share.   Full year results included $1.638 billion, or $4.58 per diluted share, of net unfavorable items as follows:

·                  $961 million, or $2.70 per diluted share, loss on impairment of assets included in discontinued operations;

·                  $756 million, or $2.11 per diluted share, primarily for estimated loss contingencies associated with the Macondo well incident;

·                  $135 million, or $0.38 per diluted share, additional charges associated with the estimated 2011 goodwill impairment of the contract drilling services reporting unit and the 2012 impairment of the intangible assets of ADTI;

·                  $66 million, or $0.19 per diluted share, net loss from discontinued operations, offset by;

·                  $232 million or $0.67 per diluted share, related to favorable discrete taxes and other items; and

·                  $48 million, or $0.13 per diluted share, gain on the sale of two deepwater floaters.

After consideration of these net unfavorable items, adjusted earnings from continuing operations for the full year 2012 were $1.419 billion, or $3.96 per diluted share.  A reconciliation of the non-GAAP adjusted net income and diluted earnings per share is included in the accompanying schedules.

During the fourth quarter of 2012, the company reclassified its drilling management services operations in the U.S. Gulf of Mexico to discontinued operations, reducing revenues and operating and maintenance expenses by $103 million and $112 million, respectively, for the year ended December 31, 2012.

Interest expense, net of amounts capitalized, was $723 million for the full year 2012, compared with $621 million for the full year 2011.  Capitalized interest for the full year 2012 was $54 million, compared with $39 million in 2011.   Interest income was $56 million for the full year 2012, compared with $44 million in 2011.

For the full year 2012, cash flow from operating activities totaled $2.708 billion, compared with $1.825 billion for 2011.

For the year ended December 31, 2011, net loss attributable to controlling interest totaled $5.754 billion, or $17.88 per diluted share, resulting primarily from the loss on the goodwill impairment associated with the contract drilling services reporting unit of $5.2 billion, or $16.15 per diluted share; and the estimated loss contingencies associated with the Macondo well incident of $1.0 billion, or $3.10 per diluted share.

Full Year 2013 Guidance Summary

The following table is a summary of the company’s full year 2013 guidance for key income statement and balance sheet items.  This information is based on current expectations and certain management assumptions, and is subject to change.

*  Other Revenues includes Drilling Management Services, recharge revenues, and other miscellaneous revenues.

** Net Interest Expense is net of capitalized interest of approximately $90 million and Interest Income of approximately $50 million.

Forward-Looking Statements

Statements included in this news release including, but not limited to, those regarding estimates of Transocean’s full year 2013 guidance, goodwill or long-lived asset impairments, estimated loss contingencies associated with the Macondo well incident, are forward-looking statements that involve certain assumptions. These statements are based on currently available competitive, financial, and economic data along with our current operating plans and involve risks and uncertainties including, but not limited to, market conditions, Transocean’s results of operations, the effect and results of litigation, assessments and contingencies, and other factors detailed in “Risk Factors” and elsewhere in Transocean’s filings with the Securities and Exchange Commission. Should one or more of these risks or uncertainties materialize (or the other consequences of such a development worsen), or should underlying assumptions prove incorrect, actual outcomes may vary materially from those forecasted or expected. Transocean disclaims any intention or obligation to update publicly or revise such statements, whether as a result of new information, future events or otherwise.

Conference Call Information

Transocean will conduct a teleconference call at 10:00 a.m. EST, 4:00 p.m. CET, on Monday, March 4, 2013.  To participate, dial +1 913-312-0407 and refer to confirmation code 8254413 approximately five to 10 minutes prior to the scheduled start time of the call.

In addition, the conference call will be simultaneously broadcast over the Internet in a listen-only mode and can be accessed by logging onto Transocean’s website at www.deepwater.com and selecting “Investor Relations.” A file containing four charts that may be discussed during the conference call, titled “4Q12 Charts,” has been posted to Transocean’s website and can also be found by selecting “Investor Relations/Quarterly Toolkit.” The conference call may also be accessed via the Internet at www.CompanyBoardroom.com by typing in Transocean’s New York Stock Exchange trading symbol, “RIG.”

A telephonic replay of the conference call should be available after 3:00 p.m. EST, 9:00 p.m. CET, on March 4, 2013, and can be accessed by dialing +1 719-457-0820 or +1 888-203-1112 and referring to the confirmation code 8254413.  Also, a replay will be available through the Internet and can be accessed by visiting either of the above-referenced internet addresses. Both replay options will be available for approximately 30 days.

About Transocean

Transocean is a leading international provider of offshore contract drilling services for oil and gas wells. The company specializes in technically demanding sectors of the global offshore drilling business with a particular focus on deepwater and harsh environment drilling services, and believes that it operates one of the most versatile offshore drilling fleets in the world.

Transocean owns or has partial ownership interests in, and operates a fleet of, 82 mobile offshore drilling units consisting of 48 High-Specification Floaters (Ultra-Deepwater, Deepwater and Harsh-Environment drilling rigs), 25 Midwater Floaters and nine High-Specification Jackups. In addition, we have six Ultra-Deepwater Drillships and three High-Specification Jackups under construction.

For more information about Transocean, please visit the website www.deepwater.com.

Notes

(1) Annual Effective Tax Rate is defined as income tax expense from continuing operations excluding various discrete items (such as changes in estimates and tax on items excluded from income before income tax expense) divided by income from continuing operations before income tax expense excluding gains on sales and similar items pursuant to the accounting standards for income taxes. See the accompanying schedule entitled “Supplemental Effective Tax Rate Analysis.”

(2) Revenue efficiency is defined as actual contract drilling revenues for the measurement period divided by the maximum revenue calculated for the measurement period, expressed as a percentage.  Maximum revenue is defined as the greatest amount of contract drilling revenues the drilling unit could earn for the measurement period, excluding amounts related to incentive provisions.   See the accompanying schedule entitled “Revenue Efficiency.”

(3) Rig utilization is defined as the total number of operating days divided by the total number of available rig calendar days in the measurement period, expressed as a percentage.  See the accompanying schedule entitled “Utilization.”

(4) Effective Tax Rate is defined as income tax expense from continuing operations divided by income from continuing operations before income taxes. See the accompanying schedule entitled “Supplemental Effective Tax Rate Analysis.”

TRANSOCEAN LTD. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF OPERATIONS

(In millions, except per share data)

(Unaudited)

TRANSOCEAN LTD. AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

(In millions, except share data)

(Unaudited)

TRANSOCEAN LTD. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS

(In millions)

(Unaudited)

TRANSOCEAN LTD. AND SUBSIDIARIES

FLEET OPERATING STATISTICS

(1)         Average daily revenue is defined as contract drilling revenues earned per operating day.  An operating day is defined as a calendar day during which a rig is contracted to earn a dayrate during the firm contract period after commencement of operations.

TRANSOCEAN LTD. AND SUBSIDIARIES

FLEET OPERATING STATISTICS (continued)

(2)         Rig utilization is defined as the total number of operating days divided by the total number of available rig calendar days in the measurement period, expressed as a percentage.

(3)         Revenue efficiency is defined as actual contract drilling revenues for the measurement period divided by the maximum revenue calculation for the measurement period, expressed as a percentage.  Maximum revenue is defined as the greatest amount of contract drilling revenues the drilling unit could earn for the measurement period, excluding amounts related to incentive provisions.

TRANSOCEAN LTD. AND SUBSIDIARIES

SUPPLEMENTAL EFFECTIVE TAX RATE ANALYSIS

(In US$ millions, except percentages)

Transocean Ltd. and Subsidiaries

Non-GAAP Financial Measures and Reconciliations

Adjusted Net Income and Diluted Earnings Per Share

(in US$ millions, except per share data)