The Long Coast's Vista Point tower is found at the mouth of a river South of The Greenhouse where the "Seeds of the Past" Main Quest takes
Horizon Forbidden West Guide - IGN
The Long Coast Vista Point Horizon Forbidden West (Find Where
Vista Point: Isle of Spires - Horizon Forbidden West Guide - IGN
Vista Point: Plainsong - Horizon Forbidden West Guide - IGN
Horizon Forbidden West - Vista Point: Plainsong Walkthrough
Horizon Forbidden West - ALL Vista Point Solutions - IGN
Vista Point: The Long Coast - Horizon Forbidden West Guide - IGN
Vista Point: The Long Coast - Horizon Forbidden West Guide - IGN
Horizon Forbidden West - Vista Point - The Long Coast