Kota Kinabalu Wetland Centre protects a patch of mangrove habitat surprisingly close to the city. Boardwalks lead through the reserve, where you can look for egrets, herons, mudskippers, crabs, and the quieter life of the tidal flats.
It is not a substitute for Sabah's big rainforest and island trips, but it is valuable because it is so accessible. Come early or late in the day, bring insect repellent, and use it as a reminder that Kota Kinabalu is still tied to mangroves, estuaries, and the South China Sea.