Blue Magic on Biševo (Croatia). 'Of the numerous caves around the remote limestone island of Biševo, the Blue Grotto (Modra Špilja) is the most spectacular. On a clear morning, the sun’s rays penetrate through an underwater hole in this coastal cave, bathing the interior in a mesmerising silvery-blue light. Swimming inside is a surreal must-have experience – worth a trip to this far-out island.' http://www.lonelyplanet.com/croatia
In Borneo, deep in Sarawak’s Gunung Mulu National Park, lie the most spectacular caves on earth. Over millennia the flow of water draining from the slopes of G.Mulu towards the sea has cut deep gorges through the Park’s limestone mountains and, within the rock itself, a complex network of vast caves has been formed.
Located in Chiang Mai Province, Doi Inthanon National Park encompasses the highest mountain In Thailand, Doi Inthanon, as well as several lesser summits. The doi (mountain) is largely a granite batholith intruding a southerly extension of the Shan Hills range and forming the divide between the Nam Mae Ping river to the east and the Nam Mae Chaem river to the west. Lower elevations in the most easterly pant of the park are limestone formations and contain a number of caves.