Three castaways stranded for a week on a desert island in the western Pacific Ocean were rescued after they used palm fronds to spell out “help” on a sandy beach.

The three men, all in their 40s, were found in good health on Tuesday on Pikelot Island, an uninhabited, 32-acre islet covered by palm trees 415 miles southeast of Guam, the US Coast Guard said on Thursday.

Their identities and nationalities were not released.

Their saga began on Easter Sunday when they embarked on a voyage in a 20ft open skiff with an outboard motor from Polowat atoll, some 100 nautical miles east of where the men were found.

Six days later, after the experienced mariners failed to return, their niece alerted authorities and the US Coast Guard and Navy began a search. The initial search area spanned more than 78,000 square nautical miles.

A day later, a US Navy P-8 Poseidon aircraft spotted the sign and began the rescue effort, the Coast Guard said.

“This act of ingenuity was pivotal in guiding rescue efforts directly to their location,” US Coast Guard Lt Chelsea Garcia said.

While stranded on the island, which is part of the Federated States of Micronesia, the men had access to food and water. They also recovered their damaged skiff.

A Coast Guard photograph showed two small covered shelters near the “Help” sign. The New York Times reported this was not the first time castaways have been rescued from the island. About four years ago, three missing sailors were found after they wrote “SOS” in the sand.