A rescue effort is under way in north Mayo tonight, to free a person from a sea cave, close to Downpatrick Head.
The man was one of two people who are understood to have walked into the cave, while exploring the coastline this afternoon.
They subsequently became trapped by the rising tide.
A group of kayakers who were in the area managed to assist one of the pair to safety, but the man remains trapped.
It's believed the man is trapped at a location around 40 metres from the mouth of the cave.
Rescue teams have managed to make visual contact with him and can see that he is sheltering on a ledge above the water.
Conditions in the area are said to be relatively calm but it will be tomorrow morning before waters recede significantly from the cave.