https://creativemarket.com/brigantine/1398905-154-Vintage-Sea-Illustrations

This set contains 154 vintage engravings and hand-drawn illustrations of fish, seashells, sea creatures and corals. They have been salvaged from a number of old books, carefully digitized, improved and turned into scalable vector graphics. Most of them are highly detailed, and perfect for logo design and branding purposes, patterns, posters, stationery, and everything else you can think of. You can freely scale and recolor them according to your needs.