Ko Muk (also referred to as "Koh Mook") is an island in the Southern Andaman Coast region of Southern Thailand. Muk is the Thai word for pearl, so Ko Muk means Pearl Island. Nearly half of the island is National Park. Cliffs and mountains form the centre and northern parts of the islands with a large double sided beach to the far East point. A further beach lies to the west of the island inside the national park area.
Combined minibus and boat tickets can be booked from any Trang 'tourist information' shop. A minibus to the nearest jetty and a longtail boat to Farang Beach will cost 300 baht. The 11:00 minibus to the nearest jetty and aboard the only ferry, departing once a day, costs 250 baht. The driver of boat and minivan is the same person. If you take the latter option it's recommended to arrange accommodation and a pick-up from the Ko Muk pier, otherwise you may have a 3 km walk, depending on the location of your hotel, or 50 baht motorbike taxi ride to get anywhere on arrival. However, many hotels are within easy walking distance of the pier.
The return trip is easier and cheaper, with the same ferry departing at 08.00. With no booking fees or middleman it is possible to get the ferry for 50 baht and minivan to Trang for 100 baht, although 200 baht is the more likely combined fare. All in tickets can be purchased for 250 baht from the many travel agent shops located in Trang Town. A second ferry departs at 9.30 with an increased cost of 350 baht per person.
A tuktuk to the other side of the island will cost you 50 baht per person.
Renting a motorbike at one of the resorts near Farang Beach will be around 400 baht, while renting one on the other side of the island (in the fishermans village) will be only 250 baht.
Emerald Cave is a cave located on the west coast of Koh Muk Island, - The paradise island of Koh Muk and emerald cave are part of the Trang Provence, Southern Thailand. The cave has a narrow 20m long tunnel. The cave can be entered either by swimming or by using a kayak
Map : https://goo.gl/maps/MKsh8UYeqgKwnBWy7