Which is it? Saltwater or Salt Water Pros?
The one-word saltwater is an adjective that describes salty bodies of water, the water of such bodies, and the life that lives in such bodies. The two-word salt water is correct in all other uses. It’s a noun phrase, with the adjective salt modifying the noun water. Similar distinctions apply to freshwater and fresh water.
Some publishers use the hyphenated phrasal adjective salt-water instead of saltwater, but the one-word form has been around a long time and is listed in most new dictionaries.
There you have it - that's why we're saltwater pros, not salt water pros, or salt-water pros!