A demonstration of regelation:

You need:
  1. A big block of ice
  2. A thin, strong wire
  3. Two weights
Procedure:
Tie the weights to either end of the wire. Place the ice in a location such that the weights can dangle down over the sides of the block. Place the wire atop the block and wait.
Diagram:

      +---------+
      |+-------+|
      ||       ||
      ||  ice  ||
      ||       ||
      |+-------+|
      |         |
      O         O
     OOO       OOO
     OOO       OOO
     OOO       OOO

After some time, you'll find the wire is has sunk down through the ice and is embedded within it. The ice above and below the wire will be solid - the pressure exerted by the wire has melted a path down through the ice, and the ice has regelled behind it.