Belize will blow your mind
The second to last country I visited in Central America was Belize. I almost didn't go, being short on time and money, and a lot of other travelers I had met on the road had also skipped Belize so I wasn't getting a lot of feedback on what there was to do there.
Then somebody recommended the island of Caye Caulker. I googled it, saw one picture and my mind was changed. Off to Belize. I want to lay around with islanders and eat fish I'd never seen before and get sunburned.
I actually flew in on a tiny might-crash-at-any-moment-plane from Honduras, the short flight costing me less than $100 US and saving me two days of driving and crossing borders. It still took me a boat, taxi, motorbike and two buses to get to my destination, but I was used to the complexity of traveling by then.
I was meeting a friend in Caye Caulker so I didn't have time to mess around too much on the mainland. After the speed boat to the island, I was treated with sights like this:
Caye Caulker is slow, in the best kind of way. The Caribbean lifestyle rules all here. Nobody is in a rush to do anything (except the speed boats - carting you from paradise to paradise). The food comes out at it's own time, businesses just close when the people stop coming in for the day, and everybody has time to stop and talk.
I could go on and on about Caye Caulker. The only thing it doesn't have: nightlife. The relaxing continues through the night, and small, intimate gatherings are way more common than open bars. Not that I had any problem with that.
Moral of the story: Visit Belize. Visit before the crowds and the pollution reaches here. While the reefs are still intact, and the people still relaxed.