20 Carcharodon Megalodons..... the extinct Giant White Shark... a relative of the recent Great White shark (Carcharodon carcharias)

but the Megaldon..... up to 50 feet in length.... 15 tons in weight
which a jaw..... 7feet wide

teeth up to 7 inches in length and wideness

20 of them

against Namor, the Sub-Mariner

has Namor a chance to survive ?