The cache is a large ammo can with logbook and pen as well as an assortment of swag items. There is plenty of room for trackables and swaps.
The cache is located on the top of Orona Island and at the southern end. There are various ways to climb onto the top of the island, but the most sensible and easiest has been marked for you.
The final coordinates have been averaged three times due to the tree cover overhead. You shouldn't have too much trouble locating the cache, however once reaching the clearing at the southern end of the island, take ten steps back in a NW direction and cache is located at the base of one of the larger trees.
Please be careful when attempting this cache! Check the tides before making your way over and if walking, only attempt on an outgoing/low tide. There is no real way of accessing the island, sometimes the most direct route may not be the easiest! Please be careful when on the island as there are steep drops and the ground could disappear quickly. But most importantly, have fun and don't get too covered in mud!! 
Tide info here: visit link
KiwiLeon and Greenblat