The U.S. Coast Guard rescued two mariners from their sinking boat near Molokini Crater off of Maui Wednesday night and is supervising its attempted removal.

Their 44-foot sailing vessel, Orion, sunk in about 70 feet of water off the northeast end of the crater as the mariners were on the second leg of a voyage from California to Oahu, following a stop in Hilo. The cause of the grounding is unknown at this time. The owner is exploring options for its removal in consultation with the Coast Guard, federal and state agencies and commercial salvors.

“We’re working closely with our partner agencies to respond to this grounding in a sensitive area off Maui,” said Lt. Brock Blaisdell, command duty officer, Coast Guard Sector Honolulu in a news release. “There is a small amount of fuel aboard and no sheen has been seen. These mariners acted quickly to call for help and don lifejackets when it was necessary to abandon ship. We remind anyone operating in the area to keep a sharp lookout and be cautious as the vessel is now underwater.”

The call for assistance came over VHF-FM Channel 16 at 9:31 p.m. Wednesday, prompting the launch of the RB-M crew and an MH-65 Dolphin helicopter crew from Air Station Barbers Point.

The RB-M crew arrived on scene within 50 minutes and rescued the master and passenger aboard. Both were transported to the station at Maalaea Boat Harbor. No injuries were reported.

The Coast Guard said the Orion is considered a minor pollution threat, with a maximum potential of 40 gallons of diesel fuel, 10 gallons of gasoline and two marine batteries. Coast Guard personnel will revisit the site Thursday to further assess the situation.

The National Oceanic and Atmospheric Association, state Department of Land and Natural Resources and Office of Boating Safety have been notified. The Coast Guard has also issued a notice to mariners of the possible hazard to navigation.