Aitutaki - Cook Islands
I bet you're wondering where this came from...well, you need look no further than the Cook Islands to find this particular location (yes, part of the group that Captain James Cook discovered, but not directly discovered by him - this location was found by William Bligh). A 30-mile protective reef surrounds the island, but you can still explore it on foot and is a perfect destination for a picnic or snorkeling in the clear water.
It's just another fun place to visit while you're on your way through the south pacific. You're probably better off flying into nearby Rarotonga (RAR) and catching a transport over. Virgin Australia and Air New Zealand offer flights from Auckland or via greater Australia if you're in the neighborhood and want to check this place out!