Does some shoal searching?

• Looks beneath the surface, in a way
• Divers' gear
• Attachments for skin divers
• U-shaped devices
• Face mask attachments
• Swims with sharks, say
• Skin diving devices
• Swims with tubes
• Visits a coral reef, perhaps

Wiktionary Word definitions in Wiktionary
n. (plural of snorkel English)