Imagine finding yourself in a secret cave deep beneath the earth’s surface. You blink to try to adjust your eyes to the darkness, but it’s no use. You can’t see a thing. The air around you is extremely humid and you feel a bit uncomfortable. All of a sudden, you remember that you brought a flashlight. You turn it on and can’t believe your eyes. There are giant crystals everywhere. Some are clear, others are light blue, and all of them tower above you. You could explore the cave for hours.

Although this sounds like a place that can exist only in the human imagination, it’s as real as Mount Everest or Ha Long Bay in Vietnam. This is the Giant Crystal Cave in Naica, Mexico. The cave is nearly 300 meters beneath the earth’s surface. It’s full of giant crystals that are made out of selenite. Some of these crystals are as large as 12 meters in length. The crystals are so big because of their unique environment. They have been in very hot water for over 500,000 years.

Before you book a plane ticket to Mexico, there’s one thing you should know. Unfortunately, the cave is not open to the public. The atmosphere inside the cave is hot enough to kill you. Temperatures can be as high as 58 degrees Celsius. Thus, anyone exploring the cave needs to wear special protective equipment.

Even the professionals with protective gear won’t be able to enjoy the cave for long. Exposure to air has a damaging effect on the giant crystals. Therefore, the organization that is responsible for the cave plans to flood it with water after enough photos and videos have been taken.

想像一下，倘若你發現自己置身在地底深處一座隱密的洞窟裡，會是什麼感覺？你試著眨眼，讓雙眼適應漆黑的環境，但卻於事無補，完全伸手不見五指。周遭空氣極為潮濕，讓人有點不適。突然間，你想起自己有把手電筒。點亮手電筒後，眼前景象令你瞠目結舌──到處都是巨型水晶，有些水晶清澈透明，有些水晶呈現淡藍色，所有水晶高聳過人。你甚至可以在此洞穴裡探索數小時之久。

雖然這聽起來像是幻想出來的世界，但卻如聖母峰或越南下龍灣一樣真實，這裡就是墨西哥奈卡的「巨型水晶洞」。此水晶洞距離地表將近300 公尺深，遍布著亞硒酸鹽所構成的巨型水晶。有些水晶的長度可達12 公尺。地底洞窟的獨特環境，以及超過50 萬年來浸沒於高溫熱水中，即是如此碩大水晶結構的成因。

不過，在你預訂飛往墨西哥的機票前，一定得弄清楚，此水晶洞並未對外開放。洞室裡的環境悶熱到足以致命的地步，且溫度高達攝氏58度。因此，探勘洞窟的人員，均需穿戴特殊的防護設備。

即使是全副武裝的專業人員，也無法在此久留。由於巨型水晶洞暴露於空氣中會受損，因此負責洞窟勘查的組織，打算先拍攝足夠的照片和影片後，再灌淹水晶洞。