Labelling of noun components of a verb

In a verbal construction, like scuba diving, what is 'scuba' held to be?

I like scuba diving.

Above, 'scuba diving' is a gerund.

I like to scuba dive.

Above, 'to scuba dive' is the infinitive.

Is 'scuba' considered a noun adjunct in a verbal construction like this?

And there are plenty of other examples like this:

• to skate board
• to spear fish
• to space walk
• to home school

Scuba (occasionally SCUBA) is an acronym, standing for self-contained underwater breathing apparatus, and it is occasionally used as a noun meaning that type of equipment. For example, in Reef Fishes of Hong Kong by Y Sadovy and A Cornish

Fishes were recorded by underwater visuaL census surveys, using SCUBA, and collected by fishing gears such as nets, hooks, traps and anaesthetics.

More often its used to modify other nouns, dive, tank, lessons, and even the somewhat-redundant equipment. In these cases it is thus lexically a noun but functionally a noun modifier, a role going by the name adjunct noun or attributive noun.

When scuba is combined with a verb, usually with forms of to dive, it forms a compound verb, a noun+verb form in which the noun is subsumed into a digram that functions as a verb:

I will scuba dive at the Great Barrier Reef tomorrow.