Bryn-Engan Quarry

Turquoise water fills this old slate quarry like a forgotten swimming pool, creating one of Anglesey's most striking sights. The colour is genuinely startling - an almost tropical blue that photographs beautifully but feels oddly out of place in rural Wales.

Walking around the rim takes about twenty minutes, with decent paths that families can manage easily enough. The steep quarry walls drop straight down into surprisingly deep water, so keep youngsters well back from the edges. Swimming isn't officially encouraged, though that doesn't stop the odd brave soul on warm days.

History buffs will appreciate the remnants of the old slate workings scattered about. You can still make out where the quarrymen hauled their stone up the hillside, and there's something rather moving about seeing nature reclaim this industrial site so completely.

Located just outside Tyn-y-Gongl, it's a proper hidden spot that most tourists miss entirely. No facilities whatsoever - not even a car park, really - so you'll be pulling up on the verge and walking in. Takes about an hour to see everything, though photographers could easily spend longer chasing that perfect shot of the impossible blue water.

For families staying at nearby parks like Glan Gors or Benllech Glamping, it makes a decent morning detour before heading to the proper beaches. Just don't expect facilities or crowds - this one's all about that stunning colour contrast.