Been certified for 5 years now, and for the corsair, yes you would have to be since its about 100 ft down. The reef dives were at around 40-45 ft. I would definitely say try it if you want, but you have to be as serious as if you were learning to fly a plane, yes it's easier (why I don't have a license yet) but there are as many ways that things can go horribly wrong in my opinion. Had a dive in Akumal, ruined by old gear that started leaking air, had to use friends secondary breather the rest of the dive, so it was about a 1/3 to 1/2 as long as planned.