it is just an estimate. it was after some of the dive techniques that i needed to learn (i've forgotten what was it). She didn't go OW1, 2 3, sequencially, but jumping one after another. so, i didn't really remember which is which. but at the end, all i know is, i've completed everything
after completing it, and while we still have time/air, she guided me, swimming along the reefs, slowly ascending, before we surfaced. so, it happened when we were at about 12m.
btw, this center brought students straight to the sea, well, it's the shore. i was trained all along at the shore. I questioned them why, because during that time, water was rough, it was the raining season, visibility was poor. although i was about 3-4ft away from my instructor to observw what was she performing, i could hardly see her. Her answer to me was we try to expose our students to the sea as much as possible, so that they will feel easy when they really go to the sea.