Peggy and I just completed a ten day traverse from Gunung Mulu National Park Headqurters to Limbang, near the Brunei Border. It was a grand, tropical adventure capping our six weeks in Borneo.
Gunung Mulu National Park is a World Heritage Site that the Lonely Planet Borneo guide says should be at the top of any Borneo traveller's list. I've made ten trips to Borneo since 1994, including remote trips to Kalimantan and expeditions to Sabah, and would have to agree that Mulu belongs at the top of a packrafter's list of places to go in Borneo, if the packrafter is interested in wilderness, tropical forest, wild animals and crazy buttressed trees, caves and karst, as well as cultural experiences. It also has good infrastructure on either end and is relatively safe.
We flew in from Miri to Mulu (no roads lead there) and spent a few days exploring the caves there, both the "Show Caves" (lit and on paved walks) and an "Adventure Cave" (by head lamp and rope). The caves offer "Planet Earth" type experiences and far surpassed our expectations (we did no rafting in the caves, however). There are over 160 km of mapped chambers in just the Clearwater Cave System. We then spent three days walking into, climbing to the Pinnacles, and walking out on the Headhunter's Trail. The Pinnacles are spectacular limestone blades and the climb to them is much more physical and fun (with ladders and hand holds) than Sabah's 13,000 foot granite Kinabalu. Our guide to the Pinnacles (needed for the climb) was a Penan (well described in Eric Hansens's adventure classic, "Stranger in the Forest: On foot Across Borneo") who shared great native viewpoints and knowledge with us.
The Headhunters Trail (a historic native portage route between the Melinau and Terikan drainages) ended at a dock where trekkers get picked up by long boat. We opted to raft down the river which was, as Peggy said, "An easy beginners' packafting river" with good bird watching and many many PR2 rapids. We had no maps, but I'd guess it to be about 25 miles of boating to the Iban Longhouse at Melaban. We spent an extra day at Mentawai Ranger Station on the border of the Park, a night in an Iban Longhouse drinking rice wine and sharing hunting stories with the people there, and also camped in the forest downstream of Melaban (spooking ourselves -- but that story you'll have to find on our blog).
We eventually caught a longboat ride to Medamit as the river gets very slow, hot, and open to the sun, and we just do not really enjoy flatwater paddling much. At the logging camp that's Medamit we bought a huge, super-tasty Durian for $3, one of the best we've ever had, and ate it on the bus ride to Limbang, then took an express boat from Limbang to Labuan and on to Kota Kinabalu, Sabah, the next day.
I'd like to do the trip again but start in the Kelabit Highlands at Bareo.....Trippling its length I guess, and spending time with other local cultures including the Kelabit and more time with the Penan.