BOWLING BALL BEACH, CALIFORNIA, USA

Compared to green sand or vanishing tides, 'round rocks' don't initially sound like reason enough to visit this Californian beach. And yet, when you get down there and see the 'bowling balls' sitting like some tidy giant's game on the sand, you can't help but get a thrill. Best seen at low tide, the rocks are freakily round and freakily regular, and clustered together as if they've been placed there. The truth is, they're stubborn. The softer rock around them washed away, but these tough customers withstood the waves.

If you're driving, take Highway 1. The Bowling Balls are on the Mendocino Coast; take the Schooner Gulch Road off the highway.

GLASS BEACH, CALIFORNIA, USA

This beach is a testament to nature's amazing ability to turn trash into treasure. Overlooked by cliff s, this place was once seen as just a convenient dumping ground for Fort Braggs' garbage. Up until the late 1960s, folks would hurl their refuse – including old cars and appliances – straight over the cliff s and into the oceans. Finally the authorities put a stop to it. Over the ensuing decades, the sea performed a remarkable conjuring act, acting like a huge tumbler to winnow out the glass and turn it smooth. These days the beach resembles a gem shop. People used to collect the glass, but that's now forbidden.

Follow Fort Bragg's Elm Street to its end and then hike down the dirt trail to the beach. Take care, the path can be treacherous.