57m/187ft - single tank, air. (57m is exactly MOD with air at 1.4 pO2).
Tiputa pass in Rangiroa.
Part of 3 star CMAS certification (max depth 60m), with another instructor, a very competent one.
I was pretty narc'd, it was rather dark (gets dark down there, even in Tahiti with 300ft viz), and...