The North and South Poles are covered in ice that can be very thick. They never fully melt and refreeze every winter when they receive the fewest amount of sunlight. During the seasons of the fewest light the oceans will begin to freeze creating ice floes that can eventually turn into one big ice pack. Icebergs can break off the ice caps or glaciers to become small islands of ice that are big on the surface and even larger underneath the water. Underneath are pictures of the ice caps, icebergs, and a comparison of the ice cap from winter and summer. There is also a video link for a video showing an iceberg breaking apart.
North Ice Cap
North Ice Cap
South Ice Cap
Iceberg
Video of iceberg breaking into the ocean
Comparison of ice growth from winter to summer