For HiddenHorror:
I am a proponent of guerrilla warfare and weakening the enemy's forces (especially when losing). I always look for unconventional ways to wage war. I use seafaring in two ways:
1. "Gatherer." Quickly collect everything that doesn't float well + scout coastal areas without leaving the ship. I use this very rarely.
2. A more interesting approach: "Pirate." But only for large bodies of water. Plundering everyone and everything. Usually, you can easily gather a group of pirates that can actually turn into a deadly campaign (naval tactics + sea bonuses = super (fast, protected, hard-hitting) pirates). Enemies at sea usually don't have a large army with them. You can even get an artifact from them. The island with pirates is plundered repeatedly, and in between, the pirate ranks are replenished. In short, you need to become a "worker of the knife and axe, a romantic of the open road."
There are also various seafaring tricks that are not immediately obvious...