"Baywatch" is back ... and so are the babes! TMZ was at the casting call to capture all the chaos as the beach filled with L.A.'s finest -- and we don't mean the cops! 😏

Watch the video ... the worlds of BBLs, double-Ds and CPR all collided Wednesday as actors and actresses vied for the dream job of slow-running on the beach.

One 77-year-old hopeful actually worked on the original as a stuntwoman for Pamela Anderson! She said Pamela was very nice to work with ... "she just didn't want to ruin her hair" by jumping in the water.

We also ran into actors David Chokachi, who played Cody Madison on the original series, and Stephen Amell, who's been cast to play Hobie -- all grown up now -- in the reboot ... check out what they had to say about the physicality of working on this particular title.

And, watch the video above to see the auditioners give their best slow-motion beach run as pretend lifeguards ...

The upcoming series is reportedly expected to start production this spring ... be ready!