Coral reefs worldwide are attracting increasing numbers of scuba divers, leading to growing concern about damage. There is now
a need to manage diver behaviour closely, especially as many dive companies offer unlimited, unsupervised day and night diving
from shore. We observed 353 divers in St. Lucia and noted all their contacts with the reef during entire dives to quantify rates of
damage and seek ways of reducing it. Divers using a camera caused significantly more contacts with the reef than did those without
cameras (mean 0.4 versus 0.1 contacts min1), as did shore versus boat dives (mean 0.5 versus 0.2 contacts min1) and night versus
day dives (mean 1.0 versus 0.4 contacts min1). We tested the effect of a one-sentence inclusion in a regular dive briefing given by
local staff that asked divers to avoid touching the reef. We also examined the effect of dive leader intervention on rates of diver
contact with the reef. Briefing alone had no effect on diver contact rates, or on the probability of a diver breaking living substrate.
However, dive leader intervention when a diver was seen to touch the reef reduced mean contact rates from 0.3 to 0.1 contacts min1
for both shore and boat dives, and from 0.2 to 0.1 contacts min1 for boat dives. Given that briefings alone are insufficient to reduce
diver damage, we suggest that divers need close supervision, and that dive leaders must manage diver behaviour in situ.