I have one flowerbed plastic pond that is 15 years old. So with care they can last. It is small, only about 200 gallons. I've never walked in it. I don't think that is a good idea. Are you considering a very small flowerbed type or one of those large plastic ponds? In my opinion, I would go with a liner if you are going large. I am editing this because I should have mentioned that there are no fish in my flowerbed pond. Only frogs and lots of plants. 200 gallons is just too small for fish. My larger ponds have fish but not the small plastic pond.