A nice walk or - recommended - a short snorkeling or swimming trip brings you to a little beach where you can find shells, coconuts and/or a geocache.
When you walk or better snorkel further southwest there is a hidden beach with clear water and a magnificent underwater-world to discover. Much, much, much better than the bay you probably come from. :)
The container is a petling with a litlle shell inside. Good Luck with the find.