Craters on bottom of pool

[dford8583]

We have owned this pool since beginning of 2020. It is an older pool built probably around 2006ish. It had had the liner relo laced and the current liner is about 4 years old.
I have noticed that there are what looks like hills and craters in the lined surface. It seems like it has gotten worse over time. I am wondering if this cratering and unsmooth texture is normal or if it is something I should be concerned about

 

[JohnT]

That seems like a lot, but they look like heel marks. Are they in the deep end and shallow end both? Do you know if there is sand, concrete, cement/vermiculite or something else under the liner?

 

[dford8583]

That seems like a lot, but they look like heel marks. Are they in the deep end and shallow end both? Do you know if there is sand, concrete, cement/vermiculite or something else under the liner?

I do not know. We bought the house and the pool in 2020. They seem more prominent in the shallow end but there is some everywhere it seems.