Local floods, not world wide floods that require 9 metres of water per hour falling on every square cm of earth for 40 days and 40 nightsThe typical tidal rise in the open ocean presently is about 2 feet. This can grow to 38 feet in some places. All in the amount of water and the resistance to it.
In the open ocean a tsunami might rise to 3 feet or so.
Both of those things flood.
A few inches higher water means mucho feet when it hits land. The tides never stop. An all water planet has a wave going around it all of the time.
Have you seen many all water planets?