Ah man, I went for the first time off a reef in Cozumel, Mexico and it was the most bittersweet experience of my life. As soon I was submerged in the water it was unlike anything I had ever seen before. You've seen plenty of videos/commercials of people scuba diving, but to see all of the beautiful colors and life in the reef in person was incredible. The downside was that i had a splitting headache from getting the bends but laying on the beach for an hour afterwards helped take care of that!