Connected by a 30-minute boat ride across the Gulf of Thailand, the sister islands of Koh Samui and Koh Phangan are the grandaddies of Thailand’s travel party scene. But while Koh Samui may have a reputation for raucous nightclubs and Koh Phangan’s popularity was founded on glow-stick-lit full-moon parties, they both now have another side to them. Whether you want to spend your days doing yoga overlooking the sea, explore a tropical detox programme or seek spiritual balance meditating in a cave — these islands can cater for all.