Water behind Liner

I have a water "bubble" between the liner and the concrete, in the deep end where the tapered wall meets the pool floor. The bubble is about 3' long and 1' high.

The pool is in its 2nd year, and we live on high ground with good drainage. I have no idea how this water got there:confused:.

The only thing I can think of is that once last year when we were out of town, a huge rainstorm raised the water level to deck level. I can see how water could have got in above the liner, but doubt this would have gone unnoticed for a year.

I've read a couple posts here but I'm a little confused.

Some imply just leave it and let it drain out naturally, but what if there is no crack in the concrete to drain through?

Other posts suggest running a hose between the liner and vacuuming the water up. I don't know how to guide the hose down between the steel vertical wall and the liner, and then between the concrete and the tapered wall to the bubble 8ft under water without damaging the liner.

I'm thinking about closing the pool for the winter in the next couple weeks. Even when I drop the water level for winter, I can't see how I could do this.

Should I leave this to the pros, try something myself, or do nothing?

If it were me I'd call in the experts for that problem.

Is it possible it's been there all along? I had a bubble when my pool was filled rapidly (firehose) years ago but luckily was on the wall. Because it was filled so fast the bubble didn't escape and they vented it up the side. I'm thinking you have an air bubble, and a tough one to get to.

Edit: I don't think it would hurt anything to leave it, but if I were you I'd call the experts to vent it. It's easy to vent the sidewall but getting below that would be tough.