Originally Posted by
Wondering Beard
For what you describe, I'd say 5 atm and up. The more "up", the more security but no need to go over 10 atm.
Personally, If I was going to find myself on a boat that I could fall off or get pushed off, I'd go with 10 atm, but a shower, plunging hands in the water to retrieve something or being hosed by your niece, 5 atm is fine.
At 10 atm you can also "dive" in the sense that, unless it's a professional dive with all the equipment and going to a wreck deep underwater, you likely won't ever go past 100 meters. I saw an interview with a retired SEAL where he said that in none of his water ops did he go below 100.