Located on the gorgeous Italian island of Capri, the stunning Grotta Azzurra, or Blue Cave, has intense blue waters that almost look like they're glowing.
New Zealand's Coromandel Peninsula on the north island has one of the most beautiful coastlines in the world, and Cathedral Cove is a photogenic sea cave that can be found there by walking from Hahei Beach.
A romantic spot with plenty of adventure, the sea caves in Bayfield Wisconsin's Apostle Islands in Bayfield turn into otherworldly ice caves in the winter.
The Marble Caves, or Capillas de Mármol, are located in Patagonia, Chile. These black and white caves are one of the world's strangest natural wonders, especially with their striking contrast to the clear blue waters.
Not far from the colorful beach of Porto Ferro in Sardinia, Italy, Neptune's Grotto, or Grotto di Nettuno as it's called locally, is a large cave with impressive stalagmites and stalactites as well as giant columns.