Great Snorkeling North of Negril Jamaica
I found some great snorkeling north of Negril, Jamaica. I am in Negril right now (April 2015) and have been snorkeling all around the area. I can highly recommend the reef by Calico Jack's Island just offshore of Half Moon Beach, which is 6-8 miles north of the last hotels of Negril's famous stretch of beach.
When you reach Half Moon Beach (by taxi usually), a boat takes you from the shore to the little island, and will drop you in the water at the far end of the shallow water reef to swim back. We found very clear visibility, lots of live coral of all the various types found in Jamaica, forests of purple sea fans, and mostly small fish like damsels, tangs, wrasses, and juveniles of other types (seems like a nursery of sorts). We saw a juvenile French Angelfish, several polka-dotted nudibranchs, an orange starfish, live conch, many powder Blue Tangs, etc.
The island is also a great place to hang out. They have a new little driftwood and thatch bar on it called The Pirate Shack, and from there all you see is wild coastline all around you. Great experience, and very nice locals.
Snorkeling the rest of Negril area has been enjoyable but not quite as impressive. Off the west end's rocky shoreline to the south (near Rick's Cafe) is good visibility once again, but coral and fish are more limited (the presence of Lionfish may be a factor). But we did see an awesome and intelligent octopus that was interested in our camera.
Along Negril's Seven Mile Beach are some beautiful Spotted Eagle Rays flapping along over its shallow sand bottom, but otherwise nothing until you get out to the reef farther offshore, which is supposed to be very good from reports I've heard, but I haven't been there yet.