@NEBU_KURO Ocean floor mapping expeditions perhaps. These sparse and higher detail lines going in random directions are from paths that surveying ships have taken I believe. The rectangular area you're wondering about seems to be a systemically surveyed area for a reason or another.
Medallion's humming... that can only mean one thing! It's time to announce The Witcher 3: Wild Hunt - Songs of the Past! โ๏ธ
This brand new expansion for The Witcher 3: Wild Hunt will take you to the Path with Geralt of Rivia once more. Itโs being co-developed with @Fools_Theory and is coming to PC, Xbox Series X|S, and PlayStation 5 in 2027. Stay tuned for more information in late summer. โฐ