Dead Horse Bay
Can a beach be abandoned? Maybe not, but this particular stretch of oceanfront isn't one the masses seek out and there's a very good reason for that—it's full of trash (and now radiation). Back in the 1850s, the marshland and beach were surrounded by horse-rendering plants (where dead horses were made into glue and fertilizer), garbage incinerators, and oil factories. The horses' remains were just dumped into the water. As you can imagine, it wasn't a pleasant scene. Around the turn of the 20th century, when horses were being replaced with automobiles, Dead Horse Bay became a landfill. By the 1930s, the dump was capped off, but that cap broke in the 50s, leaking garbage onto the beach. The junk—bottles, shoe leather, bits of plastic and a ton of other pieces of trash—still continue to wash ashore. Unfortunately, in August 2020, the National Parks Service closed Dead Horse Bay to the public after it found radiological contamination. NPS says the cleanup could take many years, which means it'll be abandoned in the meantime.
Find it: Gateway National Recreation Area (but we don't recommend you go looking right now)