DH and I went out for the day today to a seaside town. We were walking around a large, man-made boating lake (not sure how deep but it has giant pedalos on it) . There were some kids, maybe aged 7-8 playing on the edge with nets on sticks. As we approached, a girl lost balance, twisted and fell in. She went under but surfaced and quickly got herself to the side before I needed to jump in (not sure I could have helped in the water much as I'm very pregnant but I'd have tried!). DH and I pulled her out and checked her over. She was shocked but ok. The other kids had run off to get the parents who were sat at least 100 metres away on a bench and not supervising. They would have been too far away to see the incident or to help had we not been there.
AIBU to think this was an accident waiting to happen and the kids were too young to be unsupervised around the water? I'm interested to hear what ages and supervision levels people think are appropriate.