The number of kayaking rescues almost doubled across the UK over the past five years, the BBC has learned.
Kayaking and stand-up paddleboarding are both among the highest risk watersports at sea and are increasing in popularity, the RNLI said.
The number of kayaking rescues jumped from 57 in 2010 to 99 in 2014, revealed a freedom of information request to the Maritime and Coastguard Agency.
It is believed to be down to a growing interest in the sport from amateurs.
Thirty-one kayakers have died in the past five years nationally - most had communications equipment in the boat but could not access it, the RNLI said.
Source: Maritime and Coastguard Agency
Iain Bruce and his family, from Aberdeen, said the RNLI saved their lives on holiday in Cornwall in July after they drifted half a mile out to sea.
Iain and his wife Rosalind hired kayaks while their children hired paddleboards.
Mr Bruce said he believes they could have died had the lifeguards not seen them waving their paddles and come to rescue them.
"They did save our lives because where we would have landed without them I shudder to think - we had absolutely no control as to where we were going," he said.
"I fell off and had great difficulty getting back into the kayak. The swell was really quite high at this point... I found myself quite breathless."
"It really was a worry... there was no way we could physically get back on our own," he said.
Mr Bruce said they were given brief safety advice by the hire company but he felt more was necessary.
Jonathan Schofield, from the British Canoe Union, said: "We're looking at trying to offer a Kitemark for hire because it's a growing industry. There is a similar system for clubs and centres so it's extending it to the hirers' market - which is a little bit more unregulated."
The RNLI said both kayaking and stand-up paddleboarding were becoming more popular and putting more people in danger because anyone can buy or hire the vessels and go along quiet parts of coast where there are no lifeguards.
James Millidge, coastal safety manager for the South West, said: "People are likely to be along a stretch of coastline where there might not be any people, there might just be steep banking cliffs or rocky foreshore.
"If you're out on the water for three or four hours, that's plenty of time for weather conditions to change... people can get caught out."
Shore Watersports Limited, one of the biggest kayak retailers in the UK, said it sold 260 boats in 2011 and estimates that to rocket to more than 1,000 by the end of this year.
Henry Churchill from the company said most customers use them off beaches: "Sit-on-tops, which are what we specialise in, are the biggest growing sector of the paddlesport market."
The first stand-up paddleboarder rescue took place in the UK in 2007, with 50 taking place since. No deaths have been recorded.
Safety tips from the RNLI for kayaking and stand-up paddleboarding:
- Tell people when you are heading out and when you are due back
- Tell people where you are going
- If you find yourself in trouble, call out for help
- Keep communication equipment like a VHF radio or mobile phone attached to you, not just to your vessel
- If possible wear a buoyancy aid
- Wear a wetsuit to help prevent cold water shock