Well snorkeling should be awesome for you guys! We have our local reef which you can do half day snorkeling and you would get to see colorful coral gardens as well as a lot of juvenile fishes here! You also get a stop at Shark and Ray ally which is fun as well!
Then there is a full day at the Hol cHan marine reserve, which would be an amazing opportunity for you guys to swim along with bigger size fishes and coral gardens. The colors you would see here are splendid! Here its a one of a kind spot...! You will also go to shark and ray ally but this is a different location from the first one and will have an amazing time around the Nurse sharks and Sting rays!
If you guys are planning to be here in caye caulker for 3-4 days, you can also do some Fishing...half day or full day! And this gives you another wonderful experience around the waters of caye caulker and its a great time for couples to bond!

And after grill your catch of the day!
Hope you guys enjoy CC.