Thailand forum

It would help if you gave a time for your visit.

Assuming that includes your arrival day and departure day, and that you'll probably want to be back in Bangkok the day before you leave, you'll have 5 days of island time.

If you're going to travel overland, your best choice might be one of the islands in Trat province ... Koh Chang, Koh Mak, Koh Wai, Koh Kut. These are close enough to Bangkok to be reached in one day (meaning you can get back to Bangkok in one day), which will cut down greatly on your travel time.

If you're flying, then you've got lots more choices, but you may want to check the weather info for Thailand on this site before rolling the dice on a place. There will probably be rain in all the island areas.

If rain is an issue for you, you might consider going to Koh Si Chang near Si Racha, or staying on the mainland in one of the coastal towns around Prachuap Khiri Khan. These two areas get less rain than most of the other places, and they are faster and easier to reach from Bangkok.

Wherever you go, the number of tourists should be quite low so you won't be dealing with crowds, and the potential for discounts could be good.

October is tricky because everywhere tends to be in wet season. My experience is that wet season is no barrier to a good beach holiday - I've always got enough sun and never lost a full day to rain, although that can happen.
One area I tend to avoid Oct thru to late December is the southern Gulf (Kos Tao/Phangan/Samui) - about one in every 5 years it tends to get a shocker wet wise - that one in 5 aint necessarily on a regular basis, can get 2 in a row etc.

Statistically the driest island of the good ones tends to be Ko Samet which is relatively close to Bangkok. It also has the advantage that all the beaches except one are on the east coast which is sheltered from the prevailing monsoon westerlies and tends to be calmer on those 15-20% of days when the wind gets blustery and unpleasant.
Samet is touristy, particularly on weekends and Thai public holidays when the Thais arrive in numbers. But Samet has some very nice laid back beaches that are not touristy - try Ao Pudsa/Tubtim or its even quieter neighbour Ao Nuan, or further south - Ao Thian and Ao Lung Dam or Ao Wai.
One problem with Samet is it does not have particularly good snorkelling off the beach. To get this on a nice east facing quiet beach in wet season away from the southern Gulf the best bet is probably the relaxed seldom visited east coast of Phi Phi of all places. Check travelfish/Phi Phi and google Relax Resort for a praised joint on its own little beach backed by a rainforested escarpment.

Ko Kradan and Ko Ngai further south in the Andaman can also do east coast sheltered/snorkelling off the beach, but tend to be a bit dead in low season and are harder to access.

I also would recommend Koh Samed at this Time of your Travel and your Length of Stay - stay in Ao Pudsa for Quietness and just walk "around the Corner" to the white Sand Beach for some Kind of Action and Nightlife.

Samet has good beaches and snorkelling but the mozzie problem there is real bad. Enough to spoil it. October is a good time to go.

"...i was hoping for something quieter than the tourist islands but still enough to do for swimming/snorkling and some cooking classes with friendly peolpe and safe."

Krabi ticks the boxes. Mainland but islands all around