Very stupid to be on a beach by oneself, let alone swimming.
Waterways, whilst 'inviting' hold dangers'.
There're so many things to consider, the minimal being one's SAFETY, in that environment.
If at night-time, well, that's a whole different kettle of fish, & not in a good way.
I remember when going to the then TPNG, in 1965, the brochure, & 'lecture' I received from the TAA Consultant, about NOT being on a beach alone, at ANYTIME, & what I had to wear.
I can remember, as if it were yesterday, such was its' mpact on me as a very young person.