The non-negotiables
- Cash (Malaysian Ringgit) — withdrawn in Semporna. Assume no card payments and no cash machines on the island.
- Certification card and logbook (divers) — operators will ask; a photo of the card is a backup, not a substitute.
- Reef-safe sunscreen and a rash guard — the sun over shallow water is ferocious, and what washes off you ends up on the reef.
- Insect repellent — evenings on a village island are mosquito hours.
- Personal medications — plus seasickness tablets for the crossing and boat days; there is no pharmacy on Mabul.
Strongly advised
- Dry bag — boat transfers and jetty life make one earn its space daily.
- Power — Malaysia uses the UK-style three-pin Type G socket; bring the adaptor and a power bank for generator-hours schedules.
- Torch or headlamp — village walkways after dark, and the boat home from the dusk dive.
- Water bottle — refill culture beats buying plastic on an island already fighting its waste problem (see responsible travel).
- Quick-dry everything — humidity means cotton stays wet; two swimsuits mean one is always dry.
Divers and photographers
- Own mask and computer if you have them — rental fills the rest.
- Spares kit: batteries, o-rings, memory cards. The nearest camera shop is a flight away.
- A red-filter light if the mandarin dive is on your list.
Leave behind
Heels, hairdryers, drones without checking rules first, and any single-use plastic you can avoid importing. The island is small; what arrives, stays.