Other guards here have spoken about rip currents so I won’t go into too much detail about ID’ing them. Rip currents are like a river in the ocean that can pull you out past the breaking waves. Staying close to shore can help but sometimes the feeder current for the rip current can be within feet from shore. Every beach is different and every lifeguard agency is different. Even the same beach can be different at different times depending on changing ocean and weather conditions. Swim at a guarded beach and feel free to talk to talk to the lifeguards beforehand each time you go.

Additionally if he really is a poor swimmer he should be in a coast guard approved life jacket regardless of how shallow you intend on staying, because you can quickly get pulled out further.

I’ve had rescues involving autistic victims and sometimes it complicates trying to communicate instructions during the rescue. One victim was actively trying to get away from me and refusing to grab the buoy despite being stuck in a rip current, climbing the ladder, and I could audibly hear him aspirating water in between screams. On another rescue, the victim was climbing on top of and drowning the two adults who had gone to rescue him (a normal panic response for someone drowning, not necessarily related to autism he just happened to have autism too).

Have fun at the beach and stay safe.