Minecraft wiki entry for Multiplayer_PvP_bases, associated text: Built mostly like an underwater base (see above), however, fire resistance potions are best used in place of water breathing potions (for obvious reasons), and you will be moving MUCH more slowly. However, when you're finally done, it's near invisible, and most players will give up trying to reach it. Naturally, it's much easier to have each player use /sethome in the base after using /tp to reach you than having everyone swim down and wasting precious resources doing so. You should also note that most servers will let you use /spawn in the nether, so you can leave. As an extra precaution, have an emergency potion of fire resistance for every member of the faction, in case of a leak. Be sure to have no wood or wool inside any part of your base (in 1.9 this becomes less of an issue due to splash water bottles). When you're done, proceed to the next step.