The first USS Thetis was a three-masted, wooden-hulled steam whaler in the United States Navy used to rescue a polar expedition and later in the Revenue Cutter Service.

She was acquired by the U.S. Navy on 2 February 1884 to be employed by the expedition to relieve the polar exploration party under the command of Lt. Adolphus W. Greely.

Later that day, the two ships rounded Cape Sabine and, while fighting a howling gale, found Lt. Greely and six companions-alive, but weak from exposure and malnutrition.

During the five-day stay, rescuers and rescued alike received a tumultuous welcome by the assembled North Atlantic Squadron and enjoyed a warm reception given by the people of Portsmouth.

She departed New York on 24 March and began an eight-month voyage during which she stopped at Rio de Janeiro, Brazil; Montevideo, Uruguay; Valparaíso, Chile; and Callao, Peru.

On 13 October, Thetis sailed into San Francisco for voyage repairs prior to a brief cruise to Alaskan waters.

She returned to Mare Island on 9 January 1888 and remained there until 8 April when she embarked upon an extended cruise in Alaskan waters.

She spent the following five months at the Mare Island Navy Yard, undergoing repairs and preparing for another Alaska survey assignment.

By October, conditions in Central America had quieted sufficiently to allow Thetis to return to San Francisco, where she arrived on the 27th.

Two days later, she reentered the Mare Island Navy Yard and remained there until the following June At mid-month, she departed San Francisco on a four-month assignment in Alaskan waters conducting survey work and patrolling to protect fur seals from poachers.

In the spring of 1899, she was transferred temporarily to the United States Revenue Cutter Service for special duty transporting Siberian reindeer to Alaska.

In 1908, she rescued 11 members of the crew of the Japanese sealing schooner Satsuma Maru who had been stranded at Point Manby (59°41′30″N 140°18′15″W / 59.69167°N 140.30417°W / 59.69167; -140.30417 (Point Manby)) on the south-central coast of Alaska below the Malaspina Glacier since their ship's anchor cable had broken during a gale and she had been driven ashore and wrecked there on 5 November 1907.

[2] The Biological Survey of the United States Department of Agriculture sponsored Thetis on an expedition to the Leeward group of the Hawaiian Islands in 1912–13.