1. existing, occurring, or used beneath the surface of the sea

1. beneath the surface of the sea

Examples

• The underseas cable carries internet data across the Atlantic Ocean.
• Scientists discovered new species in the underseas volcanic vents.
• The submarine traveled underseas for several hours.
• Underseas exploration requires specialized equipment.
• The treasure lay underseas for centuries before being discovered.
• Marine biologists study underseas ecosystems.
• The oil rig drilled underseas to reach the reserves.