From MarineSpecies Introduced Traits Wiki
Tourism is travel for predominantly recreational or leisure purposes or the provision of services to support this leisure travel. The World Tourism Organization defines tourists as people who "travel to and stay in places outside their usual environment for not more than one consecutive year for leisure, business and other purposes not related to the exercise of an activity remunerated from within the place visited". Tourism has become a popular global leisure activity. In 2004, there were over 763 million international tourist arrivals.