A friend baked this loaf of bread following your Basic sourdough video. He asked me why he got these huge holes in the crumb. I want to run it past you to make sure my answer is correct.
I appears to me that he pretty much did everything correct but over proofed it. Everything looked good, he didn't get the maximum oven spring but pretty good. His docking was right on. The color of the crust was great.
Over proofing, right? He should have done the poke test earlier I think.