Port Lina was once a coastal trading community in southern Asgarnia, and possibly partially in Misthalin. It existed near the end of the Fourth Age.
Little is known about Port Lina. It is known to have existed roughly 212 years ago, 43 years before the discovery of runestones and the beginning of the Fifth Age. It was established roughly in the same area as modern-day Port Sarim.
Historical documents suggest that Port Lina was inhabited atleast partially by pirates, and that many ships that left the port were beset by corsair fleets once out to sea. This may have contributed to the end of the port.
Samuel Scourduel, a now-deceased wealthy landowner from Varrock, travelled to Port Lina in his middle years seeking to explore the world. Seeking to explore the world, he joined Captain Gillan aboard his ship, The Glass. Samuel Scourdel returned to Port Lina some time later on a mission to Karamja.
Sources
Excellent Log of the Journeys and Tribulations of Samuel Scourduel, Parts 1 and 2