Absolutely not safe. Perfectly legal. I’m a search and rescue technician, and when I was taking a human tracking class we were discussing natural barriers. Things that people reach and change direction without some sort of other help (boat, car, airplane, etc). The CT river was the instructors first choice. She said you couldn’t cross it. I confidently told her I could get across. Might take me down river by 10 miles but I’d eventually make it across. She told me flat out “you would die trying”. It’s a dangerous and unpredictably river. The currents are very powerful