The majority of treks in Malaysia require forethought and preparation. As well as the fierce sun, the tropical climate can unleash torrential rain without warning, which rapidly affects the condition of trails or the height of a river – what started out as a ten-hour trip can end up taking twice as long. That said, the time of year is not a hugely significant factor when planning a trek. Although in the rainy season (Nov–Feb) trails can be slow going (or even closed for safety reasons), conditions are less humid then, and the parks and adventure tours are not oversubscribed.
Treks in national parks almost always require that you go in a group with a guide; solo travellers can usually join a group once there. Costs and conditions vary between parks; each park account in the Guide contains details, while tour operators in Kuala Lumpur, Kuching, Miri and Kota Kinabalu (listed throughout) can also furnish information on conditions and options in the parks.
For inexperienced trekkers, Taman Negara is probably the best place to start, boasting the greatest range of walks, many of which can be done without a guide, while Bako National Park in southwest Sarawak offers fairly easy, day-long hikes. For the more experienced, other parks in Sarawak, especially Gunung Mulu, should offer sufficient challenges for most tastes, while Sabah’s Maliau Basin is at the very demanding end of the scale. The largely inaccessible Endau-Rompin Park in the south of Peninsular Malaysia is for serious expeditions only. Mount Kinabalu Park in Sabah is in a class of its own, the hike to the top of the mountain a demanding but highly rewarding combination of trekking and climbing.