553 dive sites in 65 countries have records of seahorses.
110 confirmed by two or more independent sources, 443 reported by one source.
Sites are ranked by evidence: first by how many independent divers logged the animal there, then by how many independent sources confirm it. "Best" here means most independently confirmed, nothing more.
All 74 seahorse sites in PhilippinesDive sites in Philippines
Seahorse sites in Dominican RepublicDive sites in Dominican Republic
All 12 seahorse sites in United StatesDive sites in United States
Seahorse sites in United KingdomDive sites in United Kingdom
Seahorse sites in Cayman IslandsDive sites in Cayman Islands
Seahorse sites in U.S. Virgin IslandsDive sites in U.S. Virgin Islands
Seahorse sites in United Arab EmiratesDive sites in United Arab Emirates