In order for a company, business, or attraction to be considered truly "sustainable tourism" they need to follow three important pillars of sustainable tourism which are socio-cultural, environmental, and economic. The socio-cultural pillar of sustainable tourism has to do with the effects on the surrounding communities.
This is similar to when developers begin tearing down old homes to make space for a new theme park. If developers are not careful, they can turn a quiet little town into a loud, littered party city. The environmental pillar deals with the effects of the tourism on the environment and trying to decrease the carbon footprint.
The economic pillar is being aware of the financial changes that tourism can bring to a city.