in the swim (of things)
knowing about and involved in what is happening in a particular situation

[TahlilGaran] Dictionary of Contemporary English ▲

in the swim
active in something, know what is going on
He is definitely in the swim. He has information about everybody.

[TahlilGaran] English Idioms Dictionary ▲

in the swim
adj. phr. Doing the same things that other people are doing; following the fashion (as in business or social affairs); busy with what most people are doing.
Jim found some college friends at the lake that summer, and soon was in the swim of things.
Mary went to New York with introductions to writers and artists, and that winter she was quite in the swim.
Antonym: OUT OF THE SWIM.

[TahlilGaran] English Idioms Dictionary ▲