What causes a nose bleed during the descent?
I am not sure that the descent is correct here or not grammatically. If it is correct so what about descend, (the)descending? Please add the reason of choice.
It is necessary to say descent/descend is the correct choice semantically to describe the job of going down into the sea from the surface during the diving. My doubts are grammatically.
During is a preposition and requires a noun or noun phrase for its object.
Descent is a noun and may be used as the object of a preposition.
What causes a nose bleed during (the)† descent?
Descend is a verb—specifically, a bare infinitive. A bare infinitive cannot be used as a noun. A marked infinitive like to descend may be used as a noun in some circumstances‡, but not as the object of a preposition—perhaps because it already has what looks and sounds like a preposition in front of it.
✲What causes a nose bleed during descend?
✲What causes a nose bleed during to descend?
Descending is also a verb—specifically, a gerund. This is a form which can be used as a noun. However, during is not usually employed with gerunds, probably because the two consecutive -ings may be confusing. Instead, we use while:
What causes a nose bleed while descending?
†The is used only if you are speaking of a specific descent, not of descents in general.
✲ marks an utterance as unacceptable
‡Specifically, as a verb complement, or as the head of a complementary clause:
OED says of descend used as a noun that it's obsolete, rare, so we'll forget that one (most native speakers wouldn't even accept it as remotely credible today).
So the choice is between gerund descending and the "dedicated" noun form descent. And idiomatically the overwhelming preference would be for descent in OP's context.
I'm not sure if it's a universal rule, but it seems to me that where there's a specific noun form available, native speakers would tend to use that, rather than use a "derived" gerund.
But where the relevant verb is also commonly used as a noun anyway (for example, walk) we probably tend to use that rather than the gerund...
Ill-fitting shoes may cause blisters during a walk. (perhaps when walking, but not during [the] walking)
