Luggage and bags:
Can bring comfortable luggage and bags.
Clothing/Shoes/Weather Gear: Lightweight, cool and casual clothes are best for the tropical climate. Shorts are acceptable for women, even in town, so long as they are not too skimpy. Visitors to places of worship must adhere to the regulations imposed. Cotton shorts and T-shirts are best for going on excursions and when trekking in the jungles.
In the evening, some establishments have their own dress code for dining. For men, this may mean a long-sleeved shirt or batik shirt. Rubber flip-flops are definitely out!
Toiletries and Medical Supplies: Bring insect repellant due to mosquitoes. Can bring basic first-aid supply kit, if you wish. But if you forgot something, not to worry. Miri has excellent pharmacies.
Photo Equipment: Can bring your favorite camera. No problem with photo supplies, because Miri has good electronic shops where you can buy supplies.
Miscellaneous: Waterproofing is advisable all year. Bring an umbrella or raincoat. Can wear comfortable sandals or good walking shoes.
Ok, this is the rainforest, so it rains a lot here... Most of the days heavy rains drop from the sky like it was the end of the world. Some days it was for just a short spell, but others it would last for hours.
Dress accordingly with the heat and humidity (not exposing a lot of meat to mosquitoes) and have always a light raincoat at your avail.
Miscellaneous: A torch may be useful when you visit the caves, but if you do not have one, it will be enough with the guide's one .