the only somewhat researched land would be doggerland an area which used to connect England to mainland europe, they regularly bring up primitive stuff like chipped flint but nothing much high than that is reported, likely a combination of anything really good being kept by the fishermen or being lost/miscategorized by the academics https://en.wikipedia.org/wiki/Doggerland doggerland is proof of the scale of sea level rise and its not done yet, we are still in an ice age which is defined by ice on the poles of the planet there is also the origin of the Atlantis myth, the first recorded mention dates right back to plato in fragments of timaeus and critias