Why does my bread have a dip in the center? I made some white bread this evening and was quite happy with it except for the dip in the center:





I suspect maybe I left it to prove too long?  it seems like the air holes are too big and it has now lost it's structure.

Recipe was for 1kg flour I halved it:

500 g flour
12.5 g oil
20 g sugar
4 g dry yeast
10 g salt
300 g water

1) Mix all dry ingredients.
2) Add water and mix till incorporated. 
3) Add oil and mix
4) Knead for 5-6 min
5) Leave for 1.5 hours
6) Place in bread tin
7) Leave for 1-1.5 hours
8) Bake at 220 C for 30 min


It was a very wet dough. I may have got the liquid measurement wrong. I ended up working it as much as I could and it remained pretty wet the whole time.

Can anyone indicate what I did wrong to cause the dip?

Apart from the dip I am quite happy with this attempt.
Two possibilities:


Your dough overproofed, or
the oven wasn't hot enough. In this scenario, the dough rises and then collapses before it can set


I would guess it was overproofed. Your recipe seems fine, though with all bread recipes, steps like "Leave for 1-1.5 hours" are highly variable depending on ambient heat in the kitchen, humidity, et cetera, and you should really employ the finger poke test to be certain.

References


http://www.kingarthurflour.com/tips/bread-troubleshooting.html
http://baking911.com/learn/baked-goods/bread/problems-and-solutions/general