HARBOR DEPTHS 

 AT LOW TIDE 



• 25 feet and over 

 9 15 to 25 feet 

 o Under 15 feet 



SHETLAND *%&„ ISLANDS 



)RKNEY £|^*ISLAN 



Peterhead 



w> Belfast^ 



Newcastle 



SKETCH MAP INDICATING THE MULTITUDE OE BRITISH HARBORS 



The United Kingdom and Ireland contain 119 seaports, of which 80, even at low tide, 

 are open to vessels drawing 14 feet of water. At average tide they will admit vessels 

 requiring much greater depths. The seas surrounding the islands are very shallow, making- 

 it easy to anchor mines to destroy shipping and also to moor nets to trap submarines. If 

 the waters of Dover Strait were to subside 100 feet, an isthmus would connect England and 

 Holland. If the waters subsided 300 feet, Ireland and the whole of the British Islands 

 would once more be connected to Continental Europe. 



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