Causes and Correlates of Unsustainable Scuba Diving Tourism on Coral Reefs

Coral reef ecosystems are major tourism destinations facing unprecedented decline. Scuba diving, often promoted as sustainable and non-extractive, can directly and indirectly degrade reefs. Using video-assisted observations and post-dive questionnaires, we quantified observed and self-reported reef contacts, damages, and attitudes among 732 scuba divers across Indonesia and the Philippines. Divers made 0.26 ± 0.02 reef contacts min⁻¹ (mean ± SE), with a few outliers responsible for disproportionately high rates. Unintentional and/or unnoticed damages dominated impacts, comprising 81.9% of damaging contacts. Divers overestimated their abilities relative to peers (illusory superiority; ∼75% rated themselves above average) and relative to observed behavior (attitude–behavior gap; underestimating reef contacts by 4.92 ± 0.93-fold; mean ± bootstrapped SE). Overconfidence was greatest among the least competent divers, consistent with the Dunning–Kruger effect. Random forest analyses identified accessory use (especially cameras), operator eco-certification status (Green Fins), peer behavior, and wildlife encounters as key correlates of reef contacts. Fixed-effects models showed contacts more than doubled when other contemporaneous divers touched the reef, and wildlife sightings increased intentional, unintentional, and damaging contacts by 220%, 85%, and 106%, respectively, revealing a tourism paradox in which wildlife encounters elevate behaviors that degrade the very habitats upon which those wildlife depend.