The ocean beds contain historical artifacts including shipwrecks with tons of valuable cargo which is impossible to catalog unlike the museums.
Our oceans are believed to host at least three million shipwrecks containing gold, silver, diamonds, and many other invaluable historic artifacts most of which have not yet been discovered. Museums around the world have cataloged all the items in their custody while in the case of artifacts underwater, the same is not possible.
Bob Ballard, an ocean explorer who discovered the wreckage of the Titanic believes that there is more history preserved underwater than in all our museums combined. Various governments have funded exploration programs to better understand the ocean and also in hope of stumbling into such lost treasures. Even though there is no proper information on the amount of treasure under the oceans, most historians believe that the ocean beds host more artifacts than what we have on land.