Exhibit 99.1

GulfMark Offshore Announces

Third Quarter 2015 Operating Results

HOUSTON, November 9, 2015—GulfMark Offshore, Inc. (“GulfMark” or the “Company”) (NYSE: GLF) today announced its results of operations for the three- and nine-month periods ended September 30, 2015. Quarterly highlights include:

For the third quarter ended September 30, 2015, revenue was $60.7 million, and net loss was $185.2 million, or $7.48 per diluted share. Included in the results are after-tax special items described below that totaled $171.6 million or $6.93 per diluted share. Quarterly loss before these special items was $13.6 million or $0.55 per diluted share.

Quintin Kneen, President and CEO, commented, “In this difficult operating environment, we are pleased with our ability to improve the aspects of our business that are under our control during the downturn. Our cost reductions continue to be strong, and we see costs falling even further in the coming quarters. Our ability to quickly reduce costs has been essential to our ability to maintain positive cash flows and decreasing debt levels.

“We are managing our working capital efficiently. We generated cash from operations during the quarter, even after taking into account our semi-annual interest payments. We paid down our revolver by $49 million during the quarter, and we improved our net debt position from last quarter. We are committed to preserving liquidity, creating operational flexibility, and continuing to reduce our level of net debt prospectively.

“Regionally, our franchise position in the North Sea region continues to perform extremely well in a difficult market. Our September utilization was the highest utilization month of the quarter, approaching 85% and reversing the downward trend we had seen for several months. Our Norwegian vessels performed well, achieving higher than 97% utilization during the quarter, and our UK vessels saw a 4 percentage point increase in utilization during the last month of the quarter. Our overall utilization in the North Sea during Q3 was 84%, while our marketed utilization was an exceptional 94%.

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November 9, 2015

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“Overall, the global market continues to be difficult, with decreasing rates and utilization. Although consolidated revenue was below guidance, we continued to make significant strides in reducing operating costs, which came in at the low end of our guidance. We anticipate maintaining positive cash flow from operations by exploiting market opportunities as they arise and furthering the expense reduction initiatives in progress. Our anticipated full-year 2015 direct operating expense savings are approximately $70 million, which is an improvement of more than $10 million since the end of the second quarter. We are confident that there are more cost savings to come in 2016. Importantly, we believe that we can accomplish these cost savings while maintaining our overall commitment to safety and quality.”

Kneen continued, “We remain focused on our previously stated goals of opportunistically selling vessels, reducing operating costs and maintaining capital discipline.”

Consolidated Third-Quarter Results

Consolidated revenue for the third quarter of 2015 was $60.7 million, compared with $74.5 million in the second quarter. Consolidated revenue fell due to a 10% sequential decrease in average day rate to $14,810 from $16,428 in the previous quarter, while utilization fell to 64% from 69% in the second quarter. Consolidated operating loss was $167.1 million, compared with $4.2 million in the second quarter. Excluding special items in both quarters, consolidated operating loss sequentially declined to $12.8 million from a loss of $2.7 million in the second quarter, due to lower revenue partially offset by lower operating and general and administrative costs.

The third quarter results include five special items totaling $171.6 million net of tax ($6.93 per diluted share), of which $168.7 million ($6.81 per diluted share) was non-cash. The Company impaired a portion of its U.S.-based fleet, U.S. construction in progress, all of its goodwill, and all of its intangible assets. As a result, these impairment charges, net of tax, include $72.0 million related to vessels and equipment and construction in progress, $22.5 million related to goodwill, and $8.5 million related to intangible assets. The Company also recorded discrete non-cash tax charges during the quarter, including a non-cash charge for the repatriation of a portion of its foreign cash. The net amount recorded for these special items was a one-time non-cash tax charge of $66.2 million. Additionally, the Company recorded workforce redundancy charges during the quarter, recorded a gain on the previously disclosed asset sale, and wrote down debt issuance costs associated with the revolving credit facilities amendments. A summary of these special charges is provided in the tables at the end of the earnings release.

Regional Results for the Third Quarter

In the North Sea region, third-quarter revenue was $33.7 million, compared with $36.6 million in the second quarter. The average day rate fell 7% to $15,985 from $17,110 in the second quarter, which was the primary reason for the decrease in revenue. Although rates fell slightly, the Company exited the summer work season with improved utilization. Utilization remained relatively flat from the prior quarter, and the Company’s utilization in the North Sea, exclusive of stacked vessels, was 94% during the third quarter. The Company has seven vessels currently stacked in the North Sea.

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Third-quarter revenue in the Southeast Asia region was $7.2 million, compared with $11.0 million in the second quarter. The change in revenue was due to a decline in average day rate of 13% to $10,331 from $11,817 in the second quarter, combined with an 11 percentage point utilization decline. The Company has three vessels currently stacked in Southeast Asia.

Third-quarter revenue for the Americas region was $19.7 million, compared with $26.9 million in the previous quarter. Average day rate decreased 15% from the prior quarter due to the continued softening in the market. Utilization decreased 8 percentage points to 47% from 55% in the second quarter, due to the continued weakness in the spot market and the effect of stacking several vessels in the U.S. Gulf of Mexico. The Company’s utilization in the Americas, exclusive of stacked vessels, was 66% during the third quarter. The Company has 13 vessels currently stacked in the Americas.

Consolidated Operating Expenses for the Third Quarter

Direct operating expenses for the third quarter were $40.5 million including the workforce redundancy charges. This is a decrease of $5.4 million, or 12%, from the second quarter. The decrease was due mainly to lower labor costs related to stacking vessels and wage reductions, combined with lower repairs and maintenance, supplies and consumables and fuel expense. Drydock expense in the third quarter was $3.9 million, slightly below the Company’s previous guidance. General and administrative expense was $13.3 million for the third quarter. Excluding exit and severance costs, general and administrative expense was $11.1 million, on the low end of the Company’s guided quarterly run rate. Including the special items mentioned previously, tax expense during the quarter was $8.0 million. The Company expects a tax rate of 35% to 40% going forward, though cash taxes will likely be close to zero in the near term as the company continues to absorb net operating losses.

Guidance

Looking forward, the Company expects revenue in the fourth quarter to be between $46 and $51 million. GulfMark expects fleet-wide utilization to be between 53% and 57% for the fourth quarter, and expects its global average day rate for the fourth quarter to decrease by approximately 7% to 10% sequentially. Due to its expense reduction initiatives, GulfMark now anticipates fourth quarter direct operating expenses to be between $31 million and $34 million, and full year direct operating expenses to be between $166 and $169 million excluding special items. This represents an additional reduction of more than $10 million or 5% from the previous annual target. Excluding special items, the Company expects general and administrative expense to be between $10 million and $11 million in the fourth quarter. The Company does not expect to incur any drydock expense during the fourth quarter, resulting in a full-year expected drydock expense of $15.3 million.

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Liquidity and Capital Commitments

Cash provided by operating activities totaled $7.9 million in the third quarter. Cash on hand at September 30, 2015, was $31.2 million, and $23.0 million was drawn on the revolving credit facilities. Total debt at September 30, 2015 was $523.6 million, and debt net of cash was $492.5 million. Net debt was reduced by approximately $2.0 million during the quarter. Net debt to book capital was 39% at the end of the quarter, and total liquidity (cash plus available revolver) was approximately $280.0 million at September 30.

Net capital expenditures during the third quarter totaled $3.1 million, which included $7.3 million of payments on the construction of new vessels and $3.3 million for vessel enhancements and other capital expenditures, offset by proceeds of $7.5 million received for the sale of one vessel. As of September 30, 2015, the Company had approximately $61.0 million of remaining capital commitments related to the construction of three vessels. The Company expects to fund these commitments from cash on hand, cash generated by operations, and borrowings under the revolving credit facilities.

Conference Call/Webcast Information

GulfMark will conduct a conference call to discuss earnings with analysts, investors and other interested parties at 9:00 a.m. Eastern Time on Monday, November 9, 2015. To participate in the call, investors in the U.S. should dial 1-888-317-6003 at least 10 minutes before the start time and when prompted, enter the conference passcode 9553386. Canada-based callers should dial 1-866-284-3684, and international callers outside of North America should dial 1-412-317-6061. The webcast of the conference call also can be accessed by visiting our website, www.gulfmark.com. An audio file of the earnings conference call will be available on the Company’s website approximately two hours after the end of the call.

GulfMark Offshore, Inc. provides marine transportation services to the energy industry through a fleet of offshore support vessels serving major offshore energy markets in the world.

Contact:      Michael Newman

                     Investor Relations          

E-mail:         Michael.Newman@GulfMark.com

                    (713) 963-9522

Certain statements and information in this press release may constitute “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. The words “believe,” “expect,” “anticipate,” “plan,” “intend,” “foresee,” “should,” “would,” “could” or other similar expressions are intended to identify forward-looking statements, which are generally not historical in nature. These forward-looking statements are based on our current expectations and beliefs concerning future developments and their potential effect on us. While management believes that these forward-looking statements are reasonable as and when made, there can be no assurance that future developments affecting us will be those that we anticipate. All comments concerning our expectations for future revenues are based on our forecasts for our existing operations. Our forward-looking statements involve significant risks and uncertainties (some of which are beyond our control) and assumptions that could cause actual results to differ materially from our historical experience and our present expectations or projections. Factors that could cause actual results to differ materially from those in the forward-looking statements include, but are not limited to: the price of oil and gas and its effect on offshore drilling, vessel utilization and day rates; industry volatility; fluctuations in the size of the offshore marine vessel fleet in areas where the Company operates; changes in competitive factors; delays or cost overruns on construction projects, and other material factors that are described from time to time in the Company’s filings with the SEC, including the Company’s Annual Report on Form 10-K, Quarterly Reports on Form 10-Q and Current Reports on Form 8-K. Consequently, the forward-looking statements contained herein should not be regarded as representations that the projected outcomes can or will be achieved. These forward-looking statements speak only as of the date hereof. We undertake no obligation to publicly update or revise any forward-looking statements after the date they are made, whether as a result of new information, future events or otherwise.

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