Visit Dunn's River Falls. I am almost hesitant to tell you what you do there (if I had known, I might not have gone), but you should definitely go. It is a hike, but well worth it for the sense of accomplishment.
Do the Dreamer snorkeling trip/booze cruise. It’s by far the best "booze cruise" I have ever been on. They offer a nice boat and fun crew.
Talk to the locals. One local explained some of the history of Jamaica and that the dialect they speak is a combination of Spanish and English. However, most people involved in the tourism industry will tone down the accent and speak English.
Quick Tips:
Mo Bay is a poor town. Most of the locals are just looking to make a buck by selling you wares or pot, getting you into their taxis, etc. I never felt unsafe, really; overwhelmed is more like it.
We were offered marijuana everywhere, by cab drivers, concierges, and people on the street. Be careful. Just say no. It is illegal in Jamaica, no matter what they say. With that said, our hotel seemed pretty lax about it. I smelled it in the hall and on the beach a few times.
If you are staying at an all-inclusive resort, bring a mug or be prepared to buy one. We thought it sounded dorky to bring one, but so many people did just that. All the drinks come in tiny 8-ounce cups. Not only is it bad for the environment, but who drinks only 8 ounces of anything? The nice insulated mugs at the resort (and at Margaritaville) are . If you go to one of the markets, they are . Or you can bring your own.
Don’t bother bringing your own beach towels. Resorts provide "towel vouchers" for you, and you can even you leave the property with one.
Best Way To Get Around:
Watch out for non-legit cabs. The legit ones have green license plates.
Most people who visit Jamaica are on a "package" deal that includes air, hotel, and roundtrip transport to/from the airport. If you don't have roundtrip transport (we didn't - see why in my Sunset Beach Resort review), it confuses everyone at the transportation desks. Luckily, one of the nice ladies at one of the desks led us to a legit taxi and bargained for us. I highly recommend having your transportation from the airport prearranged. There are all kinds of people hanging outside the airport trying to get you in their taxi and begging for money, which was a rather uncomfortable way to begin our vacation.
Getting a taxi from our hotel was always easy. It was about into town from our hotel, and we took a trip out to Dunn's River Falls for roundtrip for four people. The taxis there are generally VW buses, with two bench seats in the back.
Our hotel also had giant buses that took day trips to area sights and, at night, made hourly trips to/from Margaritaville for free.