One of their most fascinating expeditions is their visit to Botallack Mine, a copper mine on the coast where most of the workings & shafts are hundreds of feet beneath the sea. The excursion begins amusingly with Wilkie being fitted out by a gigantic miner in the appropriate clothing for a trip down a hot, dirty mine. When the miner has obligingly hoisted Wilkie’s trousers up under his armpits & folded over his sleeves several times, he’s ready at last to descend into the mine. They descend ladders until they reach a depth of 420 feet but this isn’t the bottom of the mine. The shafts descend for hundreds more feet & spread out beneath the ocean for hundreds more. They decide that they’ve gone far enough, trying to imagine the miners working for 8 hour shifts in such hot, moist, dirty conditions, and thankfully ascend to the surface.
* Thank you to everyone who told me that the picture of St Michael's Mount in the original post was actually Mont St Michel in France! I've replaced it with the Cornish Mount by Turner.