We had a cruise stop in Castries, St. Lucia and decided to visit Bike St. Lucia rather than do an excursion through the cruise line. My son and I did mountain/jungle biking through Bike St. Lucia, and my wife and daughter did the snorkeling tour through their affiliated site, Jungle Reef Adventures. We all agreed it was the best outing of our cruise!
For biking, we had a nice tour around the old plantation after we were fitted to our bikes. The bikes were in pretty good condition, and the tour was nice and friendly, and showed us the different trails we could take. Then we biked on our own until lunchtime (and could have afterward if we wanted).
The trails are decent (great for Caribbean) single and double track, and the place is nicely maintained -- also there are said to be no snakes (thanks to the importing of the Mongoose). They have trails of different levels, though most are Beginner level (as far as MTB trails are concerned), with a bit of climbing here and there but not many rock/rooty/technical sections. I was riding with my 7 year old son (who rides MTB with me a lot) and the trails were great for us -- we did not ride the hardest trail, Tinker's Trail, as I thought the climbs and drop offs might be a bit much for him.
My wife and daughter were brought from their snorkeling tour to the bike area, and we all had lunch together. They had fish and I had chicken, and both were quite good, as were the side dishes and dessert. During lunch, my wife and daughter raved about the snorkeling so much that my son and I decided to take the boat over to the snorkeling beach with them after lunch.
While there is a beach near the biking trails, the other beach they have is better for snorkeling. The water was truly crystal clear -- clearer than almost anywhere else I've been in the Caribbean. Lots of rocks/reefs not far from the beach that you could easily swim to, with TONS of different fish to see. If you've ever been snorkeling at Chankanaab in Cozumel, I'd say it is about that good.
We had a great day, and they got us back to the pier in plenty of time before our 4:30 cruise ship boarding deadline. I highly recommend Bike St. Lucia/Jungle Reef Adventures for some of the best biking AND snorkeling in the Caribbean!