sealine

noun5

1. •
   An undersea pipeline for oil, natural gas, etc.
2. •
   The coastline, seaboard.
3. •
   The horizon.
4. •
   A line used for sounding.

   • Yet what depths of the soul does Jonah's deep sealine sound! — 1851
5. •
   A line used for fishing in deep water.