legendary ice cave on the top of hintertuxer glacier in austria, natural ice palace

16000 adventure age alpen alps arc arch attraction austria austrian beautiful blue boat cave cavern clear cold cross dive europe freeze frost geological glacier green hill hintertux hintertuxer ice icecave icy inside interesting lake legendary level located minerals mountain mountains natural new paddling palace pool possibility purenature sea snow stand top tourists transparent tyrol untouched walk water white within wonder years