At the airports: Don't You know you can not go with a bottle of water through airport security? Empty it before you go, and just fill it with water again across. Much better than throwing it out and buying one. new bottle, a few minutes later.
In hotels: Take your personal care products with you. By bringing their products, that we put in the rooms are for others. Use a towel and a towel only. If the others are not disturbed, you can save the water that would be needed to wash them unnecessarily. Leave as many lights in your bedroom and you can deleted.
In National Parks and Environmental Reserves: when visiting a park or reserve you are helping animals and plants that are kept there for future generations. This money will help the park to manage the services, grow into new territories and also to educate others about nature and wildlife.