A beach house behaves like two assets glued together: a piece of scarce land, and a high-maintenance building sitting in salt air. The land tends to appreciate faster than inland property in the same country, because coastline is finite and demand for it keeps rising. The building depreciates faster than an inland one, because salt, humidity, UV and storms attack it continuously. Whether the total is a good investment depends on how much you paid for the land portion versus the building portion.
This is exactly why cheap coastal markets can outperform expensive ones. When you buy a $70,000 house in an emerging beach town, you are paying mostly for land and location, and almost nothing for structure. When you buy a $900,000 finished home in a mature market, most of the price is a building that will need $15,000–$30,000 of work per decade just to hold its condition.
