The South Sentinel Island is a small isle 27km away from Little Andaman. The closest airport to the South Sentinel Island is Veer Savarkar International Airport, Port Blair.
From Port Blair, you can take a ferry or helicopter to Hut Bay, Little Andaman. The ferry may take upto 6-8 hours. The government operated daily ferry would cost Rs. 65/-. Overnight ferries with cabins are also available. The helicopter costs Rs. 3350/-. From Little Andaman, you will have to hire a local boat to go to South Sentinel Island.
You can walk throughout the small isle easily.