Off The Coast has a beach at the top and an ocean at the bottom. The water and most of the junk above the shipwreck cannot have towers placed on them, with the exception of the large left & right pieces and the tall crane in the middle that slightly blocks line-of-sight. There are also 2 cliffs at the top of the map that block line-of-sight slightly and cannot support tower placements. Bloons enter from the bottom-left and exit at the bottom-right.
Strategy
Off The Coast is one of the easiest Advanced maps in BTD6, thanks to its relatively long length and single-lane nature. The only major difficulties are the lack of compact loops, and both the start and exit being in the water with little proximity. The abundance of both land and water allow a wide variety of strategies to work well on this map.
Its midgame strength allows an easy saveup to Comanche Commander, and this is helped by the map's single-lane nature. Conveniently, the mini-Comanche 25% track distance thresholds are roughly positioned near the "apexes" of the three wide loops.
The global range of Flagship's planes is able to get around Off The Coast's lack of compact track sections. They deal solid damage all around and can largely solo deep into the 80s. The ~17% attack speed buff Flagship provides to water towers helps greatly as well, due to the abundance of water on this map.