Chera Dip is the southernmost point of Bangladesh. The name means "the island that broke away".
You can walk there over sand and rocks, but only at low tide. The sea takes the path back when it rises, so check the tide first and leave time to return. Or take a boat from the main jetty.
Go early, before the ships dock around midday. Bring water, a hat, sandals for the rocks and a bag for your rubbish.