Cinque Island is the gem of Andamans. If you find yourself stuck in Port Blair, I suggest take a trip to Cinque Island. It will take 2.5-3 hours to reach here from Port Blair, so one can easily plan a day trip to Cinque Island. But keep in mind that one needs a special permit from government to visit this island, and getting a permit can get somewhat tricky if you don't know anyone locally. Once at Cinque Island, you will have the whole island to indulge in some snorkeling and scuba. It is worth it, so do visit. you can get it through agency or if doing snoekling or scuba through some agency they may help you to get the permit.
Hi Swechha, getting a permit for Cinque island is very difficult, you can not get in if you do not know any local. If you want to visit the place, you can get in touch with any of the charted boat owner, they have their way of getting the permit. So they can get you the permit and boat to reach the place.