Songs of the Spellbound Sea is a 336-page supplement for D&D 5E, adding 3 new classes, 31 subclasses, 7 species, backgrounds, feats, items, and more. It has four mini-settings with adventure seeds for GMs. It has 300 new spells, including the entirety of the Spells That Don't Suck project. Oh, and a full set of seafaring rules, with naval combat and upgradable ships.