A good friend of mine who is an excellent diver was with a very good DM and a well respected captain and years ago in marginal condition they were diving Chun Chakab and got caught in a south flow eddy that sometime occurs near shore. They got kicked out below the Punta Sur, the boat was frantically searching north and 1-2 hours later they were picked up in the channel by a fisherman. It happens.
Carnival week in 2016, marginal conditions, was diving Chun Chakab and wandered towards shore, looking for Lion fish, and hit the southbound current, blink of an eye I was alone and I had to swing like hell to get back to the northbound current. I was talking to me friend later when he told me about his trip out to the channel.