Giant Beaver Dam

The Giant Beaver Dam is a structure created by wild. They can spawn on land or in the water and are approximately the size of a 1x1x1 structure. Wild Giant Beavers will become hostile if a player accesses one.

Loot
Giant Beaver Dams can contain large quantities of the following which makes them very rewarding when found.

Locations
Beavers can be found near bodies of water at specific locations on the map - a map of which is shown here.

Dams themselves can appear anywhere near the places wild spawn in. If a wild Beaver is relocated into a different zone, it will not spawn any dams.

On Ragnarok, there is an area known as the Beaver Sanctuary, that is special in that there are 3 unique beaver lodges and two actual beaver dams located with guaranteed spawns.

Harvesting Tips
The Giant Beaver Dam is an excellent source of several important resources. However, to get the most out of vandalizing beaver homes, keep the following in mind:
 * Beaver Dams will not restock their inventory. As wood is the only heavy resource spawned inside the dam, many players will harvest everything else and leave the wood inside. Throw the wood on the ground instead so that the dam is demolished, and the now-homeless Castoroides will soon build another which can then be harvested for more resources.
 * Above is true for original "little" Giant Beaver Dam, but on Ragnarok "big" Giant Beaver Dam can restock their inventory and don't need to be destroyed completely.
 * It is possible to build a Beaver Dam Farm, by building walls around a beaver and allowing them to build a dam at a more desirable location.
 * If possible, do not kill the Castoroides protecting the dams. as they may not respawn to build more. One tactic is to take a flyer, open and close the dam to aggro the nearby beavers, then lead them somewhere up- or downstream before flying out of render range. Once the Castoroides no longer render on your screen they will no longer be hostile to you. As they will be far away from their dams, you may return and loot at your leisure.
 * Beaver dams can spawn both above and under the water, on cliffsides, and even in seemingly inaccessible nooks and crannies. If you see several Castoroides but no dams, they may be in hard-to-see spots, including behind waterfalls, under a resource node (often a large stone), or deep in murky water.
 * Underwater dams require special preparation and caution. Castoroides are considerably faster and more maneuverable underwater, and may be difficult to spot in the distance. Also, the moment the player begins swimming they will attract the attention of every Megapiranha in range. Be ready to kill these before you harvest the dam!
 * Two of the locations that spawn dams on The Island are on the edge of swamp biomes. Players should clear the area of Sarcos and Titanoboas in addition to other threats, especially if you'll have to swim to the dam.
 * While a player can create a "dam farm" by importing beavers to another area, beavers outside of their native environment or in an insufficiently large enclosed area in their native environment will despawn in a few hours.
 * A dam is "claimed" when it is built by a Castoroides, which will try to stay within a few dozen meters of its claimed dam. If the beaver moves out of range, the dam becomes unclaimed. At present, it appears that a damless Castoroides will not claim an unclaimed dam and will instead spawn a new one of its own.
 * Looting the dam without hurting the Castoroides is made considerably easier with a Beelzebufo, especially in shallow water and cliffsides were out hopping the beaver is considerably easier. Have the frog next to you, and the moment you acquire the building material and dart away unharmed.
 * Placing a bed next to the dam before looting is a great strategy, as beavers will not harvest or take from your corpse after looting. Simply respawn and take the loot from your body.
 * The easiest way to raid the dam without hurting the Castoroides is by using a raft. If you can reach a land dam or hover over a water dam from the raft or just below it in the water, you can easily remove all the supplies in the dam and remount the raft without a scratch. The wood in the dam can be used to repair the raft for damage and a sheltered one will block the beavers out.