Nearly all visitors to Ko Adang come from Ko Lipe; see the Lipe travel page for info on getting there.
Shared longtail boats to Adang cost 100 baht per person, one way, and can be arranged at a few different boat taxi stands on Lipe’s Sunrise Beach, including one in front of the school and another at Captain Yut’s near Castaway Resort. Expect to pay around 400 baht for a round trip from Pattaya Beach.
If taking a day trip you can pay for a round trip with the same boat; otherwise it’s usually no problem to hang around the beach and ask the boat drivers for a lift back to Lipe at any time before late afternoon.
Ko Adang is also included on a number of boat tours from Ko Lipe.