Steffan Roberts Vernon, 33, from Caernarfon, died at the Llanberis beauty spot in Gwynedd, on Sunday alongside Alexander Hadley, 21, from nearby Dinorwig.
Two others, aged 27 and 25, were treated in hospital and later released.
Police believe the men got into difficulty while swimming in the "extremely cold" water.
Friends have been posting tributes on a Facebook page called 'Steffan Vernon and why we all love him'.
Debbie Ann Williams wrote: "So sad such a lovely smiley soul the gentle giant who always had a big hug 4 everyone rip steff xxxx"
Eve Maria posted: "Xxx always ready for an adventure full of smiles and a beautiful crazy laugh xxx"
Emma O'Neill said: "Some souls leave the world a far better place than when they arrived....just by being a part of it."
The coroner for north west Wales has launched an investigation into their deaths and an inquest will be opened at a later date.
Tributes have been paid to a "gentle giant" who died while swimming near a waterfall in a north Wales village.