Guide:Surviving in the Ocean

Getting Started
In all worlds, there are two Oceans, one at either side of the map. The Oceans don't really play a very big part in-game; they mainly provide accessories to further improve your suitability in water. Additionally, oceans are the only source of Shark Fins, Coral, and Pirate Maps as well as the dye materials Black Ink and Purple Mucos. It is usually visited to summon Duke Fishron, a powerful aquatic enemy that can only be summoned near Oceans.

The main threat of the Ocean is the very water it is composed of, which poses a serious risk to players in the form of drowning. Second to this are the Sharks, which can be a massive threat to unprepared players.

Entry
Because most of the water-based gear is found in the ocean, it's unlikely that you'll be able to charge right in. As such, it is important to proceed with caution. If you only want to loot the Water Chests beneath the surface, consider building a bridge of Platforms, diving in, and using a Magic Mirror or Recall Potion to teleport out. If you're lucky and come across Flippers, you should be able to safely swim to the surface before running out of breath. A Breathing Reed can help extend your breath in future visits, but by the time you reach it, your breath will be dangerously low already.

Additionally, the Flipper Potion can be of great use, as it allows you to move fast, swim in the water, can be made without any ocean items. The Gills Potion is a close second, as it allows you to breathe underwater for 2 minutes, although it leaves you at risk from Sharks and can only be made from Coral found in the ocean.

Combat
As mentioned before, a great threat in the ocean comes in the form of Sharks. The countless Pink Jellyfish in the ocean can also be a problem if they swarm you, but their glowing allows them to be detected and evaded much easier. To deal with enemies, consider bringing a set of Iron armor or higher, as well as a Spear, Boomerang, or any Gem Staff. Lower knockback weapons such as early Swords are useful against the Pink Jellyfish and Crabs, although their weak knockback is inefficient against Sharks.

Visibility is also a concern down at the ocean depths. While Pink Jellyfish give off light, Sharks and Crabs do not, and can strike unexpectedly from the darkness at any time. The most readily source of aquatic lighting available would be the Glowsticks dropped by jellyfish, as torches do not work underwater. The Mining Helmet bought from the merchant can also help provide light, as well as the rarer Jellyfish Necklace dropped by jellyfish. Furthermore, a Hunter Potion can be used to clearly see the locations of enemies.

What to do there?
Once you have gotten to either of the Oceans, you can do a few things.
 * 1) Harvest Coral.
 * 2) Kill the sharks for Shark Fins and the Diving Helmet.
 * 3) Loot the chests.
 * 4) Make an underwater home away from home.
 * 5) Collect water in Buckets to make Obsidian.
 * 6) Go to the very edge of the map (the last 2 squares that you can get to.) And dig down to flood The Underworld.
 * 7) Build Atlantis!
 * 8) Summon Duke Fishron! (only available in hardmode)

Fishing
Fishing in the ocean yields some of the most powerful pre-hardmode loot in the game, all of which can be obtained as soon as the player obtains a fishing rod and bait. This makes ocean fishing one of the most effective ways to gain an efficient head-start in the beginning.

Fishing in the ocean will grant the following loot:

Redux
If you're returning to the ocean for more resources, using ocean items will make this much easier. A Diving Helmet dropped by Sharks will allow you to breathe underwater for much longer, and and can be combined into Diving Gear and Jellyfish Diving Gear to allow swimming and providing light.

No new enemies appear in the ocean during Hardmode, although enemies have a chance to drop the Pirate Map. Any Wings will let you easily surface from the ocean, and a Neptune's Shell or better will act as a permanent Flipper and Gills potion, making the ocean trivially easy to survive in.