I would like to do a day dive from Phuket and wanted to know if anyone has recommendations on dives to take. We will be staying at the Hilton Arcadia in Karon for the first part of the trip and then the JW Marriott at the Northern end of the island for the second half, so I'm not sure if it makes sense to dive at one part of the island. Any feedback would be appreciated. Thanks.

Dive trips are 'off island', snorkeling around Phi Phi and other islands, nothing around those hotels as such, try www.phuketjettour.com, unless you are there in top peak season no need to book, just arrange from your hotel, prices are pretty standard.

find a dive operator with a comfortable fast boat and go to koh phi phi. i went diving last month there and it was fantastic. lots of reef fish, lion fish, clown fish, clams, turtles, corals and sea fans....world class....

Any specific dives you would recommend?

we did our dives on koh phi phi lea ...two little islands north of koh phi phi don. near maya bay (where the beach was filmed).
usually, dive operators will take you to the best site available on any particular day.
we had very clear water the first dive and about 50-60 ft visibility the next dive.

danny
I spent 4 days last week on a dive boat out of Chalong Bay Phuket. We used Sea Bees, a German run company that I HIGHLY recommend. They have the program down perfectly. They have an assortment of dive trips in the Andaman Sea as well as the Similians. A Thai woman is on board each day to cook great authentic meals included in the price. I don't dive but went along each day anyway, and though they're not a snorkel tour operation, I was able to do some anyway. I'll get details from MDH who dove each day and get back to you asap with which dives they did and what he might recommend. It was actually the reason we went to Phuket and we have no regrets.

Danny,
I am currently researching a dive trip to Phuket. This website was recommended to me by a dive travel agent- has details of day trips and livaboards. It looks to be pretty comprehensive:
http://www.siamdivers.com/dive/day-trips.htm