Minecraft wiki entry for Multiplayer_PvP_bases, associated text: If all is done correctly, you'll have an underground fortress deep below, don't put it in the ocean, as people can use a low render distance to glitch into your base, instead, make a water wall, with hybrid defenses. Be sure to cover the air-shaft used to access the base, or disguise it to make it look natural, hiding the trapdoor. This can seem like paranoia but it's always good to have more stealth and safety. Your base will take a very long time to be found even if enemies are hunting you relentlessly.