I was wondering why there really is no good underwater mod. Especially considering that underwater and especially oceans are an area Minecraft is utterly lacking currently. Currently the best "ocean related" mods out there are probably Redpower and Buildcraft (for adding Valcanoes and Oil wells into the ocean) which in itself is quite a sad fact. Just throwing a few ideas out there, this is not a mod and (atleast I) will never make it one (since I suck at coding) A few things a Underwater Mod could do: Improvements on vanilla mechanics: Improved Fishing. Fish are now actual entities (reproducing and capped). They will slowly swim towards the new improved fishing rod (you could also perhaps dig up some worms while digging dirt perhaps. Improved Squid. Nimbler, smaller and with a chance to flee (in an ink cloud upon being attacked). Also now only in Ocean biomes. Perhaps improved boats... Ocean World Generation: Shipwrecks with treasure. Sunken treasures Coral Reefs and Seaweed Fields (certain luminescent Plants and Corals perhaps) Perhaps 1 underwater ore? More Fish: Different species of Fish and Clams. All with their special traits. Can all be caught using fishing rods or other tools. They are bound to habitats/food sources or Territories. There number is capped based on the size of the watermass and the avaibilty of habitat enviroment (like corals) food (other fish) or space between groups of these fish (Territory) All those could offer special traits and products and could be aggresive/poisenous/electrecuting or easily scared. Perhaps A fish that creates Air bubbles that fill up your gauge or a fish that creates light and when killed give 1-3 glowstone dust. Perhaps a Forestry-esque Fish-genetic system. World generated fish usually wouldn't interbred (just not found together in a breedable way, meaning that you could perhaps just find Fish A, Fish B, but Fish A and B can't breed since Fish A actually eats Fish B. Add onto this clams (which couldn't be crossed with fish Various Items: Diving Suit Fishing Net (no range, but catches the fish if you manage to click it directly) Not so good on easily scared fish Fish Tank. Multiblock structure, basically works like a normal watermass (and thus also needs to be of fitting size for the fish. Allows for easy management of fish (you don't need to catch them and can take them out using an GUI.) Goes for every objects in the tank including habitat items or special food. In the case of fish-genetics a tool to analyze them could be cool. Various Food Items (Fugi, Clam-meat, Caviar, etc.) that all could provide various buffs or have other uses. Electric eels could be used as 1 time batteries for other mods Treasure chests (chests that don't create a ugly looking air-bubble, a quality that all natural underwater items could share. I don't know, but I really feel it's a big weakness of Minecraft and one that isn't really affected by the modding scene up to now.