The effect of crowding on tourist satisfaction is a widely studied aspect. Its knowledge is valuable not only to guide ordering of tourism activity but also to ensure a satisfactory experience that contributes to its economic sustainability. However, studies of this type are scarce in the context of whale watching tourism. Therefore, this research aims to evaluate tourist satisfaction and crowding in the practice of humpback whale-watching in Puerto López-Ecuador. At the methodological level, a survey was applied to 340 tourists who observed whales in the June-September 2017 season. Data analysis was based on descriptive record, the structuring of an importanceperformance analysis matrix, principal components analysis and binary logistic regression model. Unlike others, this research incorporated the calculation of a perceived crowding threshold and the analysis of the relationship between perceived crowding of boats and people on board. Among main results, the study finds that crowding influences tourist satisfaction when four or more boats coincide at a sighting site. In that sense, the activity in Puerto López is satisfactory in the face of a reported crowding scenario of 3.7 boats and 16.3 people per boat, on average. The limitations of this study are its exploratory nature because it is based on a non-probabilistic sampling and the questionnaire application exclusively in standard capacity boats, without considering those of 35 passengers.