Only 15 km from Kuching (and 5 km from the Damai Beach Resort (where I have stayed three times while at the magical, annual Rainforest World Music Festival) is the Kuching Wetlands National Park (2002) in the estuarine reaches of two rivers.
It’s also where I have twice planted mangrove trees as part of the “Greening of the Festival” which Sarawak Tourism does with all the festivals it hosts, helping offset the carbon I’ve spent getting to Malaysian Borneo.
The park is a mostly saline mangrove system of many waterways and tidal creeks connecting the two major rivers that form the boundaries of the park.
An important spawning and nursery ground for fish and prawn species and it also has a wide diversity of wildlife, including proboscis monkeys, long-tailed macaque monkeys, silver-leaf monkeys, monitor lizards, estuarine crocodiles and a range of bird life, including kingfishers, white-bellied sea eagles and shore birds, including the rare lesser adjutant stork. In 2005 Malaysia designated the park as a Ramsar site, a wetland of international importance.
To explore this park you need to travel on the river and a number of tour operators offer coastal and river cruises in and around the park.
To read more about eco-tourism in Malaysian Borneo see my small book (A love letter to Malaysian Borneo or, can this travel writer be green) which has been entered in the Malaysian Tourism 2015 Awards.