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One of Martyn's diving companions, Robbie Schmittner, in a huge flooded cave in Mexico. 8 X9 X# t7 N' x. I
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Divers carry remote underwater flash guns to illuminate this image, taken in what is probably the world's biggest underwater tunnel, Weebubbie Cave beneath the remote Nullarbor Plain of western Australia.公仔箱論壇2 G$ b1 Y3 I9 t& R, k3 b
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Divers often use guide-lines to keep them on track in the murky depths. Getting lost can be fatal.
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$ d/ q% _6 W, n* ~, [, }8 stvb now,tvbnow,bttvbDeep and dark doesn't always mean cold: Jenny Pinder swims through the underwater passages of the Grotta Giusti Cave in Tuscany, Italy. where geothermal activity heats the water to an amazing 35 degrees centigrade
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* H9 |" [& E$ A/ G& Y' sos.tvboxnow.comIn another of Martyn's photos Helen Rider swims through the narrow confines of Taina Cave near Santo Domingo in the Dominican Republic. |