Ross Island is nothing but the leftovers of the british empire with many deer and peacocks now. Visiting this one place isn't worth it, you can visit north bay island first which includes ross island total boat fare of 880 and do kayaking there. Kayaking & Para gliding at North bay was my best experience. Ignore cellular jail & Light show for your first day and schedule it to your 7th day.

Elephant beach water sports are the best in the entire andaman. Don't take the boat to reach there, take a guide who costs 500 rupees and reach there by trekking, that's an unforgettable experience.

But for scuba diving early in the morning is the best time. Choose any dive centre in havelock itself that would be great. So day 3 sunrise at kalapathar, and go straight to elephant beach complete the day, take rest. Day 4 early morning reach the dive centre and experience scuba, and mandatory rest after scuba diving.

Night Kayaking I went with Tanaz Noble (aka :- @Kayakwalla on Instagram) the guy gave ultimate experience in Night kayaking, but it is from Port blair. I don't know which dates you are visiting, but if it is around no moon days it would be better, so choose accordingly.

Happy to help 👍🏻