their ice diving and a frozen morskie oko, in the high tatra mountains. they have already cut a hole in the ice and seemed quite comfortable, although the water temperature is only 4 degrees celsius. >> that is looks pretty thin. >> it is not that thin. it has several layers. snow, ice, more snow. that is why it is so dangerous, although it is 25 centimeters thick. >> they will keep in touch with walkie-talkies in the water. how do they work? >> by using ultrasound waves, the way that dolphins communicate, except we use electronics.s. the sound quality is not very good, but we understand each other. that small box makes it possible. >> we have made contact with the divers beneath me. can you hear me? how are things down there? >> the view is great. we feel like birds. we are weightless. when the air bubbles burst on the ice, it is like being in space. >> to you feel a sense of happiness when you see the strange and its is? -- wh you see the san images? >> i cannot describe it. i feel like my problems are a long way away. >> happiness may be too strong of