@kaitlyn0 Those "basements" that are built via the old method (by lowering the ground with staircases) are also fully underground, so that's not a valid criterion to distinguish them from those basements built with the basement tool.
Anyway, if your basement is flooded, it's one built with the old method, and you probably put the lot somewhere on the beach. Either relocate the lot somewhere else or replace the basement with a real one. If your house has a foundation, you will still need the old method to get to the base of the foundation and can then use the basement tool from that point on. "Real" basements can be several stories deep without flooding.