As our populations have grown, more of us have moved to the coast. As some of us have become richer, Boeing and Airbus have allowed us to indulge our desire to see the world. Coastal vessels have become faster and safer, so we expect gratification of our desire for novel experiences at sea. As all this has happened, large whales off some coasts have increased in number, evidence that some international protection measures of the 1970s have worked. The confluence of these unrelated historical processes has led to the spectacular rise of the vessel-based whale-watching industry. Nature-based tourism does not necessarily maintain environmental quality. Ecotourism is supposed to be that special subset of nature-based tourism that provides local economic benefit without environmental degradation (Goodwin 1996). Whale watching tends to be classified as ecotourism, but it does affect whales’ behavior in the short term (e.g., Corkeron 1995). The debate on how to manage whale watching has moved to whether this matters. Do “short-term” impacts have “long-term” consequences? Research to date demonstrates that anthropogenic noise is primarily responsible for the short-term behavioral changes observed. Analogs from marine hydrocarbon extraction can provide some answers to longer-term questions: use of habitat by bowhead whales seems altered by industrial activities (Schick & Urban 2000). But current thinking now calls for demonstrations of “biologically significant”—in other words, population-level— effects (e.g., International Whaling Commission 2001). How do we demonstrate these effects? Assessing the impact of dive tourism on coral reefs requires application of established impact-assessment techniques in community ecology (e.g., Plathong et al. 2000). Studies of the effects of terrestrial tourism on wildlife ask questions at the habitat scale (e.g., Burger 2000), requiring techniques that are logistically and financially beyond most research