The man, 23, had just pulled up a net off the coast of the Northern Territory when he was bitten about 09:00 local time on Thursday (23:00 GMT Wednesday). The ship was then at 70 nautical miles (130 kilometers) from the island Rat island.
Sea snakes are among the most poisonous reptiles in Australia, though they are rarely aggressive under water.
The Marine Education Society of Australia said sea snakes, of which there are various species are among the world's most venomous creatures, though don't bite unless provoked or disturbed.The Marine Education Society of Australia said sea snakes, of which there are various species are among the world's most venomous creatures, though don't bite unless provoked or disturbed.
'No time is to be lost if someone is bitten.
The accident happened off Groote Eylandt, an island in the Gulf of Carpentaria, at about 12.30pm yesterday. There are instances of divers dying within thirty minutes of being bitten'.
Emergency medical service Care Flight sent a helicopter to the boat as part of a multi-agency response but it turned around after it was apparent it was too late to help.
A NT police spokeswoman said: "Police will continue with their enquiries and a post mortem will be conducted".
The Foreign and Commonwealth Office said: 'We are supporting the family of a British man who had died in the Northern Territory and are in contact with the Australian authorities'.
It is not the first death involving a young British man aboard an Australian fishing boat in the north.
Garraway estimated the victim died within two hours of being bitten.
"It would have been prevented if there was even a modicum of compliance with the law", Mr Cavanagh said.