Ko Jum (เกาะจำ) is a small island between Ko Lanta and Krabi Town. While the south end of the island is known as Ko Jum (or Jam or Cham), the northern part is also called Ko Phu (or Pu), and local villagers take fierce pride in the two different names.
Ko Jum has three main villages and is home to about 1500 permanent local residents. On the west side of the island are about 20 resorts which provide very simple bungalow accommodation.
Most travelers arrive via the ferries that connect Ko Lanta and Krabi, which charge about 400 baht (the same price as for the entire crossing, even though Ko Jum is at the half way point). The fare can be paid on board, but pre-booking is recommended as the ferry is often full. Tickets can be bought from travel agencies in Krabi or at the main ferry offices at the old pier on Thanon Khong Ka, and with resorts on Ko Jum. Ko Jum has no jetty or dock - the ferry stops offshore and is met by longtail boats. If you've pre-booked, then a boat from your resort should be there to pick you up; otherwise simply choose one and ask for a lift to shore.
If you arrive at Krabi airport in the morning and want to take the ferry, be aware that the transport company in the airport selling tickets to Krabi Town (90B, Nov 2015), to pier Koh Lana, Koh P.P. will only take you to their stop in Krabi town, even though your tickets says something else. There they will offer you transport to the ferry and ferry ticket for 500 baht.
The Krabi-Lanta ferries run only during the high-season which typically starts between November and ends in April (it varries every year and you should check with your hotel beforehand). During the low season you would have to charter a longtail boat. From Krabi Town or Ko Lanta this will cost you around 2,500 bahts one way. You can however make the trip via Laem Kruat which will be considerably cheaper.
From Krabi Town, you can take a songthaew (small open minibus) to Laem Kruat. The songthaew should be blue and yellow in colour and you can hop on it outside of the 7/11 shop or the Siam Bank branch near Chao Fah pier. Ask the driver to confirm the destination. The cost is 50 baht. From Nua Khlong to Laem Kruat the usual cost is 40 baht.
There should be ferries from Laem Kruat to Ko Jum between 11:30 a.m. and 6 p.m. costing 50 baht. It is a 40 minute boat ride.
The songthaew stop in Nuea Klong for Laem Kruat is outside the convenience store 10 minutes walk to the right from the town's only intersection. Ferries to Ko Jum (July 2013) at 9, 10, 11.30, 13.00, 14.30, 16.00, 17.30 and 18.15 and cost 50 baht.
Ko Jum is a relatively small island and most of the population gets around on small 100-125cc motorbikes, which can be rented easily. There is also a local taxi service, comprising a motorbike and sidecar! The roads between the villages are narrow, unsealed, and frequently pot-holed and wet, and can be very challenging for inexperienced riders. There is now a concrete road surface in the three villages and on the stretch between Ban Ting Rai and Ban Koh Jum. A taxi ride from the Ko Jum ferry port to most places on Ko Jum South is 50 baht (as of May 2012). You can also be driven around if you want to see the island's main places for 400 baht (as of May 2012).
The villages are sights in themselves, with slight differences in their ways of life. Travelling around the island on a motorcycle is a fun and (mostly) safe way of sightseeing.
Most resorts will also be able to arrange daytrips with treks up to the top of Mount Pu on the northern part of the island, which has a majestic view of the islands and the Andaman Sea.
Relax in a hammock by the beach. Swim. Walk along the beach. Small hikes. Many people seem to stay here longer term just to relax and recharge. There is not a whole lot of activities to do.
Most guesthouses and resorts on the island have a kitchen, and would be happy to take your order even if you aren't staying there as a guest. Just walk down the beach until you get hungry. The meals are good, and the prices decent.
The island just recently got electricity (2008) and it's starting to get developed in the southern part. The constant loud noise from bars and partygoers, like it is at Phi Phi, has not been an issue here, but this will probably change with time. Beer and stronger drinks are available from your guesthouse, or from shops in the Ko Pu, Ting Rai and Ko Jum villages.
Respect the locals by making an effort to keep bottles of alcohol out of view, and keep in mind that many travellers come here to get a quiet break from these parties that you'll find anywhere else in Thailand.
It seems unlikely that there are any problems on Ko Jum but take usual precautions.
An exception may be dogs, particularly in low season and they may become more desperate for food and attention (which tends to come from tourists not the local people) and/or territorial. This reviewer was adopted and bitten by a dog, chased out and later prevented from entering a resort from the owners dogs and accosted by another pack in the space of three days in July 2013.
During season 2013-2014, several burglary cases occured. Valuable items such as phones, cameras and money were stolen from the rooms in various resorts.
Some people go to Ko Phi Phi or Ko Lanta via ferry. Otherwise if you want to go back to Krabi Town, just go back the opposite way you came in. The ferries back towards Krabi Town, via Laem Kruat, go from 7:15 to 8 am.