When I was growing up, my great uncle had a log cabin on an island. We'd spend a week or two there every summer, it was a blast.
The way the island was shaped, he was able to build a breakwall with rocks and
concrete. Then he spent many a day hauling in gravel (the Maine equivalent to sand). For weeks he hauled it in, dumped it behind the wall, spread it around to make a beach. The whole island was nothing but glacial rocks, so it was nice to have a beach.
Wind, rain, waves, snow...mother nature is going to do her thing. The beach lasted a few years, steadily eroding with each season. When the beach was about half gone, the movement of the
water started to carve out the stairs leading up to the camp. The breakwall had altered the normal motion of the waves and water. If left in place, it would have taken out the camp in a few years. The breakwall was removed with more effort than going in. The beached washed away, and the water went back to normal.
We were kids. We'd have swum in a swamp.