October 21, 2008

Mariner Energy Announces Deepwater Discovery at Its Dalmatian Prospect on De Soto Canyon Block 48

HOUSTON, Oct. 21 /PRNewswire-FirstCall/ -- Mariner Energy, Inc. today announced a deepwater discovery at its Dalmatian prospect located on De Soto Canyon Block 48. The well, which lies in water depths of nearly 5,900 feet, encountered approximately 120 feet (net measured depth) / 57 feet (net true vertical depth) of high quality, dry natural gas pay. Plans are to develop the well as a subsea tieback to existing infrastructure in the area. Mariner holds a 12.5% working interest in the field. Murphy Oil Corporation is the operator and holds a 50% working interest. Newfield Exploration holds a 37.5% working interest.

Scott D. Josey, Chairman, Chief Executive Officer, and President of Mariner Energy said, "Our discovery at Dalmatian leveraged off of our previous successes at Swordfish (Viosca Knoll Blocks 917/961/962) and Aconcagua (Mississippi Canyon Block 305), and is another example of the value potential in Mariner's deepwater prospect inventory. The success at Dalmatian bodes well for our additional leaseholdings in the area, which consist of working interests ranging from 10 to 12.5% in five prospects on nine contiguous blocks."

Mariner also reported that drilling continues at its Surge prospect in Garden Banks Block 334. This is near the company's Geauxpher discovery (Garden Banks Block 462) disclosed earlier this year and currently under development. Another deepwater prospect, Heidelberg, is expected to spud next month on Green Canyon Block 859. Mariner holds a 40% and 12.5% working interest in Surge and Heidelberg, respectively.

About Mariner Energy, Inc.

Mariner Energy is an independent oil and gas exploration, development, and production company headquartered in Houston, Texas, with principal operations in the Permian Basin and the Gulf of Mexico. For more information about Mariner, visit the company's website at http://www.mariner-energy.com/.

Important Information Concerning Forward-looking Statements

This press release includes forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements, other than statements of historical facts, that address activities that Mariner assumes, plans, expects, believes, projects, estimates or anticipates (and other similar expressions) will, should or may occur in the future are forward-looking statements. Our forward-looking statements generally are accompanied by words such as "may", "will", "estimate", "project", "predict", "believe", "expect", "anticipate", "potential", "plan", "goal" or other words that convey the uncertainty of future events or outcomes. Forward-looking statements in this press release are based on Mariner's current belief based on currently available information as to the outcome and timing of future events and assumptions that Mariner believes are reasonable. Mariner does not undertake to update its guidance, estimates or other forward-looking statements as conditions change or additional information becomes available. Mariner cautions that its forward-looking statements are subject to all of the risks and uncertainties normally incident to the exploration for and development, production and sale of oil and natural gas. These risks include, but are not limited to, price volatility or inflation, environmental risks, drilling and other operating risks, regulatory changes, the uncertainty inherent in estimating future oil and gas production or reserves, and other risks described in the Annual Report on Form 10-K for the fiscal year ended December 31, 2007, and other documents filed by Mariner with the Securities and Exchange Commission (SEC). Any of these factors could cause Mariner's actual results and plans to differ materially from those in the forward-looking statements. Investors are urged to read the Annual Report on Form 10-K for the year ended December 31, 2007 and other documents filed by Mariner with the SEC.

The SEC generally has permitted oil and gas companies, in their filings with the SEC, to disclose only proved reserves that a company has demonstrated by actual production or conclusive formation tests to be economically and legally producible under existing economic and operating conditions. Mariner uses the terms "probable,""possible" and "non-proved" reserves, reserve "potential" or "upside" or other descriptions of volumes of reserves potentially recoverable through additional drilling or recovery techniques that the SEC's guidelines may prohibit it from including in filings with the SEC. These estimates are by their nature more speculative than estimates of proved reserves and accordingly are subject to substantially greater risk of actually being realized by Mariner.

This press release does not constitute an offer to sell or a solicitation of an offer to buy any securities of Mariner.

Mariner Energy, Inc.

CONTACT: Patrick Cassidy of Mariner Energy, Inc., +1-713-954-5558,mobile, +1-713-261-2627, [email protected]

Web site: http://www.mariner-energy.com/