By air: Port Blair is connected by daily direct flights from Chennai and Kolkata on an array of different airlines. Most flights into Port Blair are morning and they all turnaround and return to origin. Flights during high season get booked up fast and prices for remaining seats can become astronomically priced.
Bring a good insect repellant (for sandflies on the beach at sunset!). A good sunscreen, swimsuit and wide-brimmed hat for the beach. A digital camera is ideal (film aint available). Bring a good yarn (a book) for those idle afternoons. Your PADI certification card for dive trips. Leave your mobile switched off (although a signal is available). And a nice bottle of wine, as there is not much choice on the islands.
The best time to go to the Andaman Islands is from December to May. During this period, the sea is like a mirror, the skies are blue and cloudless and the weather is warm without being uncomfortable (except for April and May which can get quite sticky!)
From June to August, the south-west monsoon is active over the islands, turning them lush green. Rains come and go, and its difficult to predict when the weather will turn bad. But expect to spend some mornings or afternoons indoors or getting wet! But you do have practically all of the islands to yourself. September and October bring a lull in the rains and the weather can be surprisingly super during some periods. November brings short but serious downpours of the north-east monsoon.
All foreign passport holders (except China, Hong Kong, Afghanistan, Myanmar, Bangladesh, and Pakistan) are issued a 30-day restricted area permit (RAP) on arrival at Port Blair airport free of charge. All you need is a valid passport and a valid Indian visa to enter the Andamans.
If you hold a diplomatic passport or a citizen of a notified country but resident in India, you must secure authorisation from the Ministry of Home Affairs, New Delhi and obtain the RAP in advance of travel. If you are a resident from a notified country, the RAP must be obtained at the time of application for visa.
Credit cards have limited acceptability in the islands, largely in Port Blair. Cash and travellers cheques can be converted at the State Bank of India or Axis Bank in Port Blair. Indian rupees are accepted everywhere.
While in the Andaman Islands, please avoid any trips that attempt contact with the indigenous tribes. Do not pick-up coral or shells on beaches (thorough checking is done in Port Blair Airport) or buy them in shops. Avoid touching marine life when snorkelling or diving. Do not waste water or energy (both are in short supply!). Bargain, but ensure that you offer a fair price for products and services. Tip generously, when service is good. Carry your trash back to the Indian mainland when you leave Port Blair!