James Reilly, 22, from Guernsey, and Ted Simpson, also 22, from Manchester, broke the Guinness world record last year in their Loch Ness tandem kayak challenge, raising more than £2,000 for cystic fibrosis.
This time round they set a new record for the fastest canoe paddle from Kingussie in the Cairngorms to Spey Bay, which they completed in 15 hours, 51 minutes and 43 seconds.
'The River Spey is the fastest flowing river in Scotland, and they paddled four times further than Loch Ness, while negotiating rapids along the way.
They have raised close on £440 to date, having set a target of £500, for the Cystic Fibrosis Trust, and Mr Reilly said they were proud to have accomplished what they set out to achieve.
'We finished at 8.45pm, after setting off at 5am with head torches before sunrise,' he said. 'We were completely spent by the end of the day, but really proud to have given it our all to raise awareness and funds for such an important cause.'
Donations can be made online at www.justgiving.com/fundraising/speyinaday.
