You have to bring a good back-pack style gadget bag with integral tripod carrier
You have to bring a good, light (pref. carbon fibre) tripod with a ball head.
You have to bring a Circular Polarizer and a couple of Graduated Neutral Density filters
You have to bring LOTS of memory cards and spare batteries
You have to bring a rain cover for your camera
You have to bring lots of cleaning supplies, lens tissue, micro-fibre cloths, sensor brush, blower-bulb
You have to bring voltage converters/plug adaptors
You have to bring waterproof pens and paper
You have to bring spare power cords, spare USB cords, and ideally a spare battery charger
You have to bring Zip-loc style bags (several sizes) to carry all of your gear in inside your pack - tropical rainstorms are alllllll kinds of fun.
You should bring a remote-release
You should bring a GPS
You should have at least two lenses, ideally something in the 12-20 2.8 range and 24-70 2.8 range, and maybe a doubler
You should bring a good flash
You should bring a small reflector/diffuser
You should have a photographer's vest
All of that will fit nicely into a relatively small pack and weigh in at less than 40 lbs (depending on your tripod).