Indonesia has many of the world’s best diving sites, among the finest of which are Pulau Bunaken off Sulawesi and Pulau Weh off northern Aceh in Sumatra. Bali has many good sites, including the famous Liberty wreck, and reputable tour operators at all major beach resorts. The best time for diving is between late April and early October. Most major beach resorts have dive centres, but once you get further afield you’ll probably have to rely on live aboard cruises or even on having your own gear. A day’s diving with two tanks, lunch and basic equipment costs anything from $30 to $100. Be sure to enquire about the reputation of the dive operators before signing up, check their PADI or equivalent accreditation and, if possible, get first-hand recommendations from other divers. Be aware that it is down to you to check your equipment, and that the purity of an air tank can be suspect, and could cause serious injury. Also check your guide’s credentials carefully, and bear in mind that you may be a long way from a decompression chamber.
Indonesia is also one of the world’s premier surfing destinations, with an enormous variety of class waves and perfect breaks. The best-known waves are found on Bali, G-Land (Grajagan) on Java and around Krui in southern Sumatra; further afield, Sumba and the Mentawai Islands are also increasingly popular.
In June and July, during the best and most consistent surf, you can expect waves to be crowded, especially in Java and Bali. Several surf companies in Kuta in Bali offer all-in surf safaris to other destinations in Indonesia. Try to bring your own board, though in the popular surf spots you can rent some decent boards on the beach. Most public transport charges extra for boards, but many surfers simply rent motorbikes with board-carrying attachments.
For detailed reviews of surf breaks, see the book Indo Surf and Lingo, available from whttp://www.indosurf.com.au and from surfshops and bookshops in Bali. Good surf websites include whttp://www.baliwaves.com, whttp://www.wannasurf.com and whttp://www.wavehunters.com
There are endless trekking opportunities in Indonesia. The most popular volcano treks include Gunung Batur on Bali and Gunung Bromo and Gunung Merapi on Java; more taxing favourites include Gunung Rinjani on Lombok and Gunung Sinabung in Sumatra. Also in Sumatra, the Gunung Leuser National Park is Southeast Asia’s largest, and includes the famous Bukit Lawang orang-utan sanctuary. The long haul to Gunung Leuser itself from Ketambe as well as many routes heading into the park from Bukit Lawang require guides, and not just to find the paths: turning up at a remote village unannounced can cause trouble, as people may mistrust outsiders, let alone Westerners. Guides are always available from local villages and tourist centres, most charging around Rp120,000–250,000 per day, although prices can be higher when arrangements are made through travel agencies.