Jesus believed the Genesis account of the flood.
Matthew 24:37-39 (also found in Luke 17:26-27)
But as the days of Noah were, so shall also the coming of the Son of man be. For as in the days that were before the flood they were eating and drinking, marrying and giving in marriage, until the day that Noah entered into the ark, And knew not until the flood came, and took them all away (Luke says, “and destroyed them all”); so shall also the coming of the Son of man be.
The writer of Hebrews believed the Genesis account of the flood.
Hebrews 11:7 By faith Noah, being warned of God of things not seen as yet, moved with fear, prepared an ark to the saving of his house; by the which he condemned the world, and became heir of the righteousness which is by faith.
Peter believed the Genesis account of the flood.
… when once the long-suffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water. (1 Peter 3:20)
And God spared not the old world, but saved Noah the eighth person, a preacher of righteousness, bringing in the flood upon the world of the ungodly. (2 Peter 2:5)