Details of  Important things to do in Andaman Nicobar Islands : –

Island Camping
For those who want to enjoy a quiet holiday in close proximate to nature, the Island Camps are just the perfect choice. Tents can be hired at Radhanagar Beach in Havelock Island.
Other islands also provide camping facilities at nominal rates between October and May, depending on the weather conditions.

Scuba Diving
A fabulous & a splendid world of marine life exists in the waters of Andaman. To explore them all, scuba diving is the best option. For scuba diving, you can contact :
Andaman & Nicobar Scuba Diving School, Wandoor.
Private drivers are also available at Samudra Tel:33159,32937 and Andaman Scuba Club, No. 7, Havelock Island, Andaman Drivers, Peerless Resort, The Samudra Drivers, Sinclair’s Bay View Hotel. Scuba Diving is in top in the list of important things to do in Andaman Nicobar islands.

Snorkeling
Have a memorable glance at colourful water world that is simply beyond imagination with snorkeling.
Snorkeling can be done near the Andaman & Nicobar Water Sports Complex, Corbin’s Cove Tourism Complex, Mahatma Gandhi Marine National Park, Havelock and other islands. Snorkels are also available on hire. Snorkeling is in top in the list of important things to do in Andaman Nicobar islands.

Trekking

Certain trekking routes have been identified for nature lovers. The prominent one running between Mt. Harriet to Madhuban. Andaman Teal House provides trekking equipment and tents.