One for the English

3 guys, 1 Irish, 1 English and 1 Scotch, are walking along the beach one day and come across a lantern and a Genie pops out of it.
"I give you each one wish, that's three wishes in total", says the Genie.
The Irish guy says, "I am a fisherman, my Dad's a fisherman, his Dad was a fisherman and my son will be one too. I want all the oceans full of fish for all eternity."
So, with a blink of the Genie's eye "AlKaZoom" the oceans were teaming with fish.
The English guy was amazed, so he said, "I want a wall around England, protecting her, so that nothing will get in for all eternity.
Again, with a blink of the Genie's eye "AlkaZoom - POOF" there was a huge wall around England. The Scot asks, "I'm very curious. Please tell me more about this wall."
The Genie explains, "Well, it's about 150 feet high, 50 feet thick, protecting England so that nothing can get in or out."
The Scot says, "Och, fill it up with water."