Sapphire Seas Online is, Where you sail around with you friends. The ships have physics so you can walk around an be all piratey, fighting ship to ship battle. Sail ships that are up to 4,000 blocks in total. If you can build it you can sail it. [ Obvious answer is stone will sink your ship and or lower it deeper into the water when you undock so use wood for best results. ]
Explore the ocean floor, control islands, Make your own factions and crews, fight sea monsters. Loot sunken ships, find old ruins of an old ancient race long since gone and find sunken treasure, become a trader or be a pirate and steal other peoples booty.
Over 20 new metal types, 100 weapons, 50 tools types, 50 types of armor possibly more. Muskets, War Axes, Pikes, Flintlocks, Cannons, and way way more.
Over 600 unique food items, And farming seed / plots that never go away simply harvest them over time. Just remember from the words of Sturges "The more you settle down the more of a target you become." Make sure to build walls and protect your land(s).