The ocean is quite a different place. Wrecks are often debris fields, and not simple plots of land.

It's not appropriate to wax indignant about remains that may have all but disintegrated into unrecognizable mud. These are not organized places, like the parks on land with paths that people walk.

Consider the wreckage of the Titanic:

https://en.wikipedia.org/wiki/Wreck_of_the_RMS_Titanic

No one can simply swin to the bottom of the ocean to pay their respects.