There are two cave complexes – Simud Hitam (Black Cave) soaring up to 90 metres high and the more accessible of the two, and Simud Putih (White Cave), where the more valuable nests are found. Simud Hitam is a five-minute walk from the registration centre. A well-maintained boardwalk gives you easy access to explore or watch the skilled harvesters at work.
The resident creatures of the caves include swiftlets (from which the nests are collected) and bats among others. Outside, other birds such as serpent eagles, bat hawks and kingfishers can be seen. You might even spot an orangutan or two. You will need to make prior arrangements for exploring the more challenging Simud Putih which calls for more serious caving.