At that rate, a 6-foot tall person would become submerged in only 15 seconds.
(a 6-foot tall person; would become; submerged in only 15 seconds; T:At that rate) (a 6-foot tall person; submerged; T:in only 15 seconds)
a 6-foot tall person a 6-foot tall person
would become submerged
submerged in only 15 seconds T:At that rate
T:in only 15 seconds