There has been a lot of talk about proper dive planning, gas management, etc. and how it applies to knowing when a dive is over. For the sake of this discussion I'm talking about either turning the dive on an out and back, or ascending for a drift dive. Some things that come easily to mind are: the plan says it over, running out of NDL time on the computer, low gas, mission accomplished.
What factors do you take into consideration when you decide the dive is over?
What factors do you take into consideration when you decide the dive is over?