I saw a low-flying hot air balloon once at Widdop reservoir, up on the moors above Hebden Bridge.
I was riding my MTB riding up a bridleway behind the reservoir when I heard a strange roaring sound from above me. When I looked up I saw a big red balloon dropping down towards the reservoir. The pilot (?) was trying frantically to get hot air in for added lift, but the balloon kept sinking lower and lower. In the end the basket hit the water in the middle of the reservoir and I thought the guy was going to end up drowning beneath the balloon. As the balloon started collapsing, the pilot gave the gas burner one really long blast and the whole thing started to go back up again. As the balloon rose into the air, hundreds of gallons of water came cascading down from the basket!
It seemed a pretty near miss at the time, but later on I began to wonder if the pilot had done it deliberately for kicks. Pretty impressive control if he did it on purpose, or pretty awful control if he didn't

!