All orca attacks happen of 20mt+ deep waters. It's common knowledge that in the hot orca areas you must be in shallow waters (20mt or less).
As in all orca attacks so far, also this one was on a hot area and on deep waters.
I don't see it anywhere on the unit table https://en.wikipedia.org/wiki/International_System_of_Units
After all, the US uses not only different units (mi vs km, yards vs meters) but also different symbols for the same units (kph vs km/h, sqm vs m², "klicks" vs km). I've even seen americans use "mt" for metric tons.
Apparently, the US is literally the only country not to use meters for depth: https://en.m.wikipedia.org/wiki/Fathom