Pack ice around Iceland was becoming a threat to navigation .
如果太多的火山热量被释放，火山口的浮冰群将会完全消失并且洞和几年前的雪一起消失。
If too much volcanic heat is discharged , the crater 's ice pack will melt away entirely and the caves will vanish along with the snows of yesteryear .
浮冰群