- Antarctica icebergs
It can be quite an unreal experience getting close up to ice bergs in small boats but a really awesome if potentially dangerous thing to do. The effect of light on and through the ice produces a world of blues and white, the berg can usually be seen for several metres below the water surface and there may be icicles hanging down as here where the ice has melted in the sun and water run across the face of the berg before freezing again. If you ever end up in this situation, make sure you have some really good sunglasses and a high factor sun screen for exposed flesh (including that little bit underneath your nose!) as the reflections and brightness especially when the sun comes out can be painfully dazzling with no-where to look that isn't brilliantly lit.
Large irregularly shaped bergs tend to be the most interesting to visit, but also the most dangerous and most unstable. They will break up at some point and they will tilt and move around a lot before settling to a new stable position. If you're in the vicinity when this happens, you may get some big pieces of ice dropped on you or at the very least there will be some major waves and disturbances of the sea. Having said that I've never heard of anyone actually being hurt in such an event - a combination of the rarity of it happening, alertness and speed of the boatman/boat and people just not going near big bergs very often in small boats.
Photo credit - Paul Ward / coolantarctica.com