I went from the baby bath tub straight to the bathtub with my son. I didn't bother with a bath seat at first. It was easier to set my son in the tub with me to kill to birds with one stone. A decision i will always regret. By this time my son could sit up on his own. So I got out of the tub to dry off as I talked to my son who was sitting in the bath. I was right there. I turned to grab his towel and I turned back to take him out next. (it was a spilt second to grab the towel that was behind me.) My son was on his back under the water with his eyes open. Of course I quickly grabbed him. He was fine. But the point is, It only took a split second and I was right there when it happened.
This was when I decided never again. I went out and got a bath seat for my son. He was still tiny enough that he was able to still fit into this one. He also didn't mind being in it as he liked the rings on it and was able to move around playing easily enough. As it is a swivel seat.
It sticks really good to the bathtub too. I sometimes had a hard time getting it off the bottom of the tub. This bath seat is really secure and safe however never leave a child alone in the seat. Not even for a spit second. As anything can happen and you don't want to regret it.
I would say to anyone who asks "What does she need when getting a baby shower gift? A bathtub ring would be my first suggestion.