You can hop out of your kayak, dive down to tie it off to the reef and swim around. Your main costs are the airfare to get there. Everything else in Thailand is relatively inexpensive. We took folding double sea kayaks, one Klepper and one Feathercraft, as baggage on the plane with no problem. I don't know if rental boats are available in Thailand.
Some resorts have boats for their customers.
Takes two-three weeks from the LA office. You must send them your passport. They'll do it quicker for a fee. That's about 19,000 miles. If you are traveling from Thailand to anywhere else buy your airline tickets in Thailand.