REYKJAVIK: Even as tourists were gazing at the phenomenon of mountain-like glaciers in Iceland's famous Vatnajokull from its foot, massive chunks of ice broke off and tumbled into the lake down causing dangerous waves of gushing waters fiercely overtaking panic-stricken visitors amidst large blocks of painful stones strewn around making escape all the more difficult, but they did.

Guides say calving of ice caps is normal but this time it was phenomenal, "exceptionally large." However, everyone was accounted for and none was injured.

Jokulsarion is a glacial bluewater lake in southeast Iceland near Vatnajokull. It is the largest glacier in Europe with glacial rivers and lagoons. The Breioamerkurjokull glacier in Vatnajokull National Park is a sought-after tourist destination.

"Everybody in the area was briefed by their guide that if a collapse happens they must leave the beach and search [for] higher ground immediately, which is exactly what happened," Mantler told AccuWeather in an email.

Mantler is a full-time mountain guide and on Sunday "was on an elevated viewpoint with my single client, so my customer was not exposed to risk at any time." Mantler said that's why he was able to continue filming the spectacular event, while others had to flee.

“Everybody who goes down there is briefed by their guides what to do in the event of a calving, but that was both exceptionally large and very close which made it a closer call than usual,” Mantler wrote on Facebook.

Calving is large blocks of solid ice breaking off glaciers and falling into the water lagoons below.