Hi Mike,
Many thanks for your reply to my post.
Thailand liveboards to Similan Islands run beginning November to end of April. My favorite time is mid Feb to end of April as than the diving conditions are great and a lot less divers as of X-mas and New Year.
From overnight trips up to week long cruises all is possible. I recommend a 4 night trip which is covering the best dive sites.
You need to calculate about US$ 550 per person for a quality low budget boat. Nationalpark fees are ~ US$ 35.
For further details just send me an email easydaythailand [ at ] gmail.com
Ciao
ED