http://ambergriscaye.com/

Take a look and the above site. Then ask your question. Most of the dive
shops store your gear . I think chilly already told you that the diving is
from dive boats. Ambergris caye is surrounded by a reef that keeps the bay
calm and is relatively shallow. you can swim off of docks,  but I don't
think you can dive. When we were in ambergris caye a few years ago, we
walked the beach and decided which dive shop to use.  They either picked you
up at your hotel or you could walk the beach. I thought the diving was good
and the choice of restaurants was excellent.