Hi Slee23. It does look like the one on Amazon, and you will be glad to know the strap is intact, so am not sure how it fell off your arm.
It was camouflaged and looked like a stone in the water as it was face down, but I have an eye for these things as I often loose my own stuff!
Not bad waterproofing as it had been in there for almost 2 months!
I can drop it off for you next time I am in Inglesport, which may be next weekend? or... I will be in the Peak this eve. or...?