Southern Thailand's Gulf coast is famous chiefly for its three fine islands of the Samui archipelago: the large and increasingly upmarket Ko Samui , the laid-back Ko Pha Ngan , site of monthly full-moon parties, and the tiny Ko Tao , which is encircled by some of Thailand's best dive sites. Other attractions seem minor by comparison, but the typically Thai seaside resort of Hua Hin has a certain charm, and the grand old temples in Nakhon Si Thammarat are worth a detour.