Neskowin Ghost Forest is a group of ancient stumps rising from the sand at Neskowin Beach State Recreation Site. They begin immediately south of Proposal Rock and extend to the end of the beach a quarter-mile or so south. They are best seen around low tide.
It's commonly believed that these ghost forests were created by rapid subsidence of shore-adjacent coastal rain forest during the Northwest's periodic massive Cascadia subduction zone earthquake/tsunami events, but apparently that's mistaken and this ghost forest (like others on Oregon's sandy beaches) was buried by dune encroachment. Other ghost forests found in estuaries were buried by subsidence and tsunamis, however. Neskowin's forest is said to be about 2000 years old.
The stumps of the ghost forest are an easy walk from Neskowin Beach State Recreation Site 39B , but you'll have to wade across Neskowin Creek to get there.
More at Alltrails, Amusing Planet, Atlas Obscura, BeachConnection.net, BeachConnection.net, OregonLive.com, Outdoor Project, Statesman-Journal, That Oregon Life, The Telegraph, TravelOregon.com, Google Image Search.
Other ghost forests on Oregon beaches.