In reply to James Oswald:
Hi...not sure about Simon Foley's website.
it wont be deathly quite, and there will be SOME people around, but bear in mind that in the very low season some resorts back on the trail close down over in Tonsai. I like it that way as the crags are a lot quieter than during high season, but the down side is that it may be a little harder to find partners, although you'll probably still find people to climb fairly quickly. A couple of the resorts closer to the beach stay open and things might start to get going again towards the time you arrive, especially at the end of your stay - but don't expect too many people at all when you first arrive. Railay will still probably be mobbed with the usual backpacker (non-climbing) crowds so you'll have no issues with finding people to socialise with. If you're on your own and staying over in Tonsai it may be a bit tricky to organise DWS and trips to some of the newer, better spots for climbng in the Krabi are (like Koh Yao Noi abd Spirit Mtn). Try emailing Elke at the climbing shop and ask if she does DWS trips at that time of year...
I know a few people who live out there who are always keen so drop me an e-mail and can put you in touch with them if you like. That way at least you can be sure you'll have someone to hook up with even if it is quiet.
Kayaks are available for rent in Tonsai and Railay and you will be able to find some OK DWS that way. To access the better stuff though you'll definitely need to head out in a longtail boat with someone who knows the islands off the coast.