If you are in central Ao Nang, Let's Relax Spa Wake Up Ao Nang has good access. Being a chain, its programme lengths are fixed, which makes the evening easy to calculate, and the guidance is clear enough for a first visit. It is well placed to walk to after an island day.
If you are staying in a Centara property, check the spa inside the resort. Let's Relax Spa - Centara Ao Nang Krabi and Let's Relax Spa - Centara Anda Dhevi Krabi are on site, so there is no transfer at all - you can go straight there on returning from a boat trip.
For a different kind of recovery, look at Wareerak Hot Spring & Wellness. Combining hot spring facilities with treatments feels different from a massage alone, and it works well on a rainy day or when an island tour is cancelled. It takes some travel from Ao Nang, so confirm round-trip transport in advance.
Avani Spa at Avani Ao Nang Cliff Krabi Resort is a clifftop resort spa, a candidate when you want the view alongside the treatment. Radarom Spa Krabi and Boossabakorn Spa & Beauty Krabi are worth noting when weighing central Ao Nang access against price.
Before booking, confirm programme duration and price, how to reserve and when to arrive, whether non-guests can use resort spas, hot spring facility rules and round-trip transport, couple room availability and the cancellation window. With relatively few registered spas, preferred slots can go first during this holiday.