After a large wave swamped their 9-foot skiff, the trio managed to swim nearly two miles at night to the remote island of Fanadik in Micronesia.
Upon arrival, they built the help sign and waited to be rescued. Three days later, they were found.
The coastguard was notified that the three men were missing on Tuesday morning after they failed to turn up for a flight from Chuuk, also in Micronesia. Four ships were subsequently deployed to try to track the lost sailors.
The three were discovered by a US Navy maritime surveillance aircraft on Thursday morning.
The men are all said to be in good spirits with no injuries.
The US Coast Guard for the Hawaiin Pacific region said on Facebook:
The men were located by a Navy P-8A aircrew Thursday in a search designed and coordinated by Coast Guard search and rescue controllers at Sector Guam. Once sighted, the information was relayed back to the family in Chuuk who launched another vessel to the island and mariners were recovered arriving safely to Pulap.
These partnerships are critical to successful search and rescue cases in remote parts of the Pacific. Ingenuity of these men to build their sign and the preparedness of having lifejackets also contributed to their safe rescue.
Micronesia comprises over 600 islands in total. A lack of resources locally sees the US Coast Guard regularly carrying out search and rescue operations in the area.