Lifeboats around Ireland were launched 377 times over the summer amid often unpredictable weather.
The RNLI said Enniskillen in Co Fermanagh was the busiest station, with its two inshore lifeboats on Lough Erne and two rescue water craft called out 23 times.
Owen Medland, RNLI training divisional inspector, said it was another busy summer for volunteers, with Dun Laoghaire, Bangor and Portrush RNLI launching 18 times each.
"There have been some stories of incredible bravery and also some stories of devastating loss," he said. "In all cases our lifeboat volunteers have shown extreme professionalism and commitment.
"Each and every call-out is different and conditions, location, duration and activity can all vary. In many cases our volunteers are involved in call-outs that go on for a number of hours throughout the night and their employers support them in their volunteering."
In one of the most memorable call-outs, a lifeboat crew in Baltimore helped save the lives of two teenage kayakers who were trapped in a cave when a wave capsized them. In challenging conditions and churning seas, a lifeboat volunteer swam into the cave and brought the pair to safety as part of a multi-agency operation, the RNLI said.
The 377 calls between June 1 and August 31 were a slight drop on last year's total of 389. Many were due to people getting caught out by the tide, problems with their vessel's engine or machinery, and an increasing range of marine leisure activities.
The RNLI said there were also a number of tragedies and many of its lifeboat crews were involved in searching for missing loved ones or in bringing them home.
During one week in August, five people died in four separate tragedies off the coasts of Cork, Mayo and Clare.
Elsewhere rising tides and rough conditions caught some sea users out and lifeboat crews rescued two swimmers in difficulty in Lough Swilly, Co Donegal, and Red Bay, Co Antrim, who were spotted in trouble by members of the public.