Diving and Drowning

[Yora]

I want to run some cave exploration adventures and I really love having sections being difficult to access because of flooding. Water breathing is a nice spell to have one character scout ahead but I also want to include this element without the whole party being able to breath underwater indefinitly. To my knowledge there aren't any official rules for diving and drowning.

Does anyone know of any systems to cover this that are somewhat plausible but not too frustrating or suicidal?

[LibraryOgre]

Dungeoneer's Survival Guide (1e version), pages 12, 13, and 14.

[Digitalelf]

The 2nd edition Player's Handbook as well as the 2e DMG have a few rules concerning this topic.

The 2nd edition DM's Reference Guide (one of the blue soft-cover books) "Of Ships and the Sea" has a chapter devoted to adventuring under water (and not just through magical aid, though it does provide magical means of doing so).

The 2e Forgotten Realms supplement "Sea of Fallen Stars" also has rules for adventuring under water (and this too is not just doing so through magical means, but also provides rules for surviving under water through the use of magic).

[denthor]

remember invisibility does not work underwater your body displaces the water forming a bubble that outlines you.