Reaver Shark

For years this was the fishing rod trick that let you skip several tiers of pickaxe on day one. That got taken away. It now breaks the same tiles a Gold Pickaxe or Platinum Pickaxe handles, and you can craft either without leaving your spawn area. If you were planning a trip to the coast just for this, do not bother.

Bad ore luck is the real case. A world that will not give you gold or platinum after an hour of caving still has an ocean, and the ocean does not care what generated underground. Fishing is a guaranteed path to the same mining power without depending on what a cave hands you. If you are already at the beach farming for other catches, take it.

With that seed the world is inverted, so the water you fish for it sits near the middle of the map around the glowing mushroom layer instead of out at the edges. Do not waste time walking to the coastline looking for a shoreline that is not where you expect.