The Caledonian Canal in Scotland connects the Scottish east coast at Inverness with the west coast near Fort William.
It runs some 100 kilometres in an North-east to South-west direction. Only one third of the entire length is man-made, the rest being formed by Loch Dochfour, Loch Ness, Loch Oich, and Loch Lochy. These lochs are part of the Great Glen, a geological fault in the Earth's crust. There are 29 locks (including eight at Neptune's Staircase), four aqueducts and 10 bridges in the course of the canal.
The canal was designed by engineer Thomas Telford and built between 1803 and 1822. Formerly of great importance for merchant and naval traffic, the canal is now mainly used by pleasure craft. It is maintained and run by British Waterways, a governmental organisation.
For instance, in France the Canal du Midi connects the Garonne river to the Mediterranean Sea, thereby completing a continuous water connection from the Atlantic Ocean to the Mediterranean Sea.
So technically, the land mass that includes the Iberian peninsula and the part of France that is south of the Garonne river and the Canal du Midi is completely surrounded by water.
Other examples of such coast-to-coast watersystems that are not considered to cut a land mass in two are the Caledonian and Forth and Clyde canals in Scotland and the Volga-Baltic Waterway in Russia.