The High Seas booster pack for Ultima Online introduced significant enhancements to the game's nautical aspects. This expansion brought new ship types, including the Tokuno, Orc, and Gargoyle ships, each customizable with different hues. Players can now engage in ship-to-ship combat with a variety of new cannons and ammunition, enhancing the tactical elements of sea battles. The expansion also added NPC ship encounters with pirates and merchant ships, making the seas more dynamic and dangerous.

Additionally, the High Seas booster included new boss encounters such as Scalis and Corgul the Soulbinder, and expanded the fishing profession with new fish types, buffs, and recipes. It also introduced new maritime-themed quests and a Sea Market, which serves as a floating town offering various services and quests