Walk in snorkeling

[Best of]

Hi,

Here is my situation. We are going out in late Jan. 2010. The 3 ports we are stopping at are Colon, Panama; Limon Costa Rica; and Belize. My husband wants to snorkel, but not by boat. He likes to be able to walk in and out of the water. Which of the above places have good walk in snorkeling and WHERE is it at. I do not want to plan my other shore trips until we know which port will be our beach day. Thanks for any and all information. :)