These three people in funny white suits, floating in those yellow rafts are—from left to right—Apollo 1's Command Pilot Virgil "Gus" Grissom, Pilot Roger B. Chaffee, and Senior Pilot Edward H. White. They look so happy.
I would have been happy too if I knew I were going to be part of the first crew to go up to space in a Saturn rocket. And perhaps the first to actually touch the Moon.
The photo was taken on a sunny day of June 1966, at Ellington AFB, near the Manned Spacecraft Center in Houston, Texas. They were practicing "water egress procedures with a full scale boilerplate model of their spacecraft". I want to believe that they got out of their suits and got some cocktails after completing the training session.
Sadly, the happy times were over too soon. These heroes died only six months after this joyful photograph, killed in a terrible fire during the pre-launch test of Apollo 1's Command Module, on Cape Canaveral's Launch Pad 34. [NASA via It's full of stars]