On holiday in Egypt last week and our three year old, Alfie, just learnt to wear goggles "wow Daddy now it looks all 3D under there". Now all he wants to do is take underwater photos. He grabbed my SLR and housing:

After a brief but frenzied struggle I managed to persuade him to start with the point and shoot. Here is his first shot (sorry about the subject matter):

His favourite technique is an interesting one, that I'm thinking of adopting myself. You must jump into the water from an elevated position (extra points for aerial tricks), then press the shutter button within milliseconds of hitting the water. The process is completed by underwater hand signals and sometimes a brief picnic on the bottom.
Alfie's technical knowledge is developing fast- he got out my pack of magic filters and sat with intense concentration as I explained how they worked. Sure enough, as I set off for the sea the next morning: "Daddy, have you remembered your Magic Filters?"