Related Clues:

• Close up - marine mammal
• Validation for a letter — tread heavily
• Marine animal
• Authenticating stamp
• Fancy stamp
• Horn-honking animal
• 59-across's ex
• Brand of squash
• Sea lion, e.g
• Passport feature
• SeaWorld barker
• Swimmer with pups
• Email doesn't require one
• Clapping animal
• Make tight