Effective management and monitoring of recreational use is fundamental in marine protected areas. The primary purpose of this study is to examine user’s satisfaction levels, crowding levels and the relationship between them at Florida Keys National Marine Sanctuary. Online surveys were sent via Qualtrics to email addresses obtained from the state of Florida during the summer of 2020. The results showed that the respondents felt very satisfied and only slightly crowded while snorkeling or scuba diving during their most recent 2019 trip in the Florida Keys, although satisfaction was still negatively impacted by crowding. An analysis of variance (ANOVA) showed that satisfaction levels were significantly lower in users who saw more people than they expected. A linear regression indicated significantly lower satisfaction with increasing age. Furthermore, a multiple regression showed that experiencing natural surroundings has a significant positive relationship in overall trip satisfaction, i.e., users that are more satisfied experiencing natural surroundings are also likely to be more satisfied with their overall trip satisfaction. This study suggests that the convergence of social and natural resource research and practices can help managers to create better policies that will maximize human benefits from, and minimize human pressures on, ocean and coastal environments.