Water bottle - 3 litres, as you need to drink plenty of water. Purifying tablets - Water is not unhealthy although its flora content is different from what you are used to. To make the water taste better and provide energy. Hiking boots - Big enough to wear thick socks. Waterproof and preferably leather - particularly for the rain forest.
Upper body wear - Minimum three layers.
Items should be wool, polypropylene or pile. Thin layers rather than heavyweight thick jumpers etc. Cotton does not provide adequate insulation. For your own daily use. Canvas bag - For porters to carry on the mountain.