Samona II was built for Willitts J. Hole, a prominent financier of Los Angeles, California as hull number 154 with keel laid 15 March 1931, launch on 25 June and maiden voyage on 31 July 1931.

The yacht was 146 ft 9 in (44.7 m) in length, 23 ft 6 in (7.2 m) beam with a draft of 10 ft 6 in (3.2 m) (11 ft (3.4 m) Navy) powered by two 500 horsepower Winton Diesel engines driving two screws. With 20,000 US gallons (76,000 l) of fuel the yacht's range was estimated as 7,000 nautical miles (8,100 mi; 13,000 km) at 14 knots (16 mph; 26 km/h) or 10,000 nautical miles (12,000 mi; 19,000 km) at 12 knots (14 mph; 22 km/h). Fresh water capacity was 11,000 US gallons (42,000 l). The design included five double staterooms with connecting baths and a large owner's stateroom. Hole was an avid fisherman who contributed to scientific collections so the yacht carried fishing boats as well as 1,000 US gallons (3,800 l) of gasoline for them in special isolated tanks.

On 1 August 1931, the day after leaving the yard on delivery, Samona II departed on a shakedown trip to Alaska. On 9 November 1931 the yacht was on the way via the Panama Canal to the east coast of South America where, after a time exploring the Amazon and Rio Negro rivers, a course was followed through the Strait of Magellan and up the west coast of South America to Los Angeles.

Willitts Hole died in 1936 and his estate, including the Willitts J. Hole Art Collection, passed eventually to his daughter Agnes Hole Rindge and son-in-law Samuel K. Rindge. The Rindges continued the yacht's collecting tradition after Hole's death into 1939.

• Built in 1931 as the yacht Samona II by Craig Shipbuilding Co., Long Beach, CA
• Purchased by the Navy 4 November 1940
• Commissioned USS Amethyst (PYc 3), 27 February 1941
• Decommissioned 2 February 1944
• Transferred to the Coast Guard 10 March 1944 and commissioned USCGC Amethyst (WPYc 3)
• Decommissioned 27 February 1946 at San Diego, CA
• Struck from the Naval Register 12 March 1946
• Transferred 11 September 1946 to the Maritime Commission for disposal
• Sold to Samuel K. Rindge of Los Angeles, CA and renamed Samona II
• Sold in the early 1950s to David P. Hamilton of Shreveport, LA and renamed Pudlo
• Sold in 1961 to Norman A. Manning of Miami, FL and renamed Explorer
• Sold in 1962 to Clarence Y. Martin of Houston, TX
• Fate unknown.