A diver is thought to have drowned off the coast of Leven.
The man, thought to be local and in his mid to late 30s, was on a boat chartered with two friends when the accident happened in Largo Bay on Thursday afternoon.
Three Kinghorn RNLI crew members were called to the scene of the incident.
The two men on the boat reported that the man had surfaced during his dive in around six metres of water and 300 yards off the coast to request weights.
The man, who has not been named, failed to resurface and the alarm was raised.
Forth Coastguard were contacted at around 1pm after a member of the public saw someone waving from a boat, and one of the men on the boat called Fife Police soon after.
The coastguard spoke to the people on board by telephone as the vessel’s VHF radio was not working.
A Royal Navy rescue helicopter was also sent to the scene to join the search, which took place in good conditions.
The search was taken over by Central Scotland Underwater Search Team, which stood down late on Thursday night and continued this morning.
Kinghorn RNLI’s spokesman Neil Chalmers said, “It would appear the person in question was diving for razor fish or something similar.
“As soon as we were alerted, we sent out our lifeboat with three lifeguards and alerted the coastguard. The police were also informed and officers from both Leven and St Andrews came out to the shore.
“Despite an extensive search, the missing diver could not be found and our search was called off at around 3.50pm, after which time the search was handed over to Central Scotland Dive Team who continued the search for the diver, who is now thought to have drowned.”
Levenmouth area committee chairman David Alexander said, “As chairman I am sure I speak on behalf of all councillors when I say this is an awful tragedy.
“Hopefully there could be a good end to this but at this stage it is looking increasingly unlikely.”
At around 9.30am this morning, Kinghorn RNLI confirmed in a Twitter update that it was launching again to continue the search.