Black Rock was awesome! I dove this around 3:00 in the afternoon and there were tons of people snorkeling. While it is crowded, there is not much "traffic" under if you are diving. The visibility was great! Lots of sea turtles, trumpet fish, unicorn tangs, and even a few black tangs. Very fun place to dive and easy to navigate. The hike to beach with Scuba gear is long, but the pathway is paved and the dive makes it worthwhile.