Scottish Canals today comprise five routes: the Highland ones the Caledonian and Crinan that have never closed, Lowland ones the Forth & Clyde and Union that closed but have reopened, and the Monkland that remains closed but supplies water. They have a pantheon of heroes : geologist James Hutton, engineers Thomas Telford, John Rennie and Hugh Baird, inventors James Watt, Scott Russell and William Symington whose vessel the  Charlotte Dundas helped measure the bow wave generated by the passage of boats. From origins in the late eighteenth and early nineteenth centuries, they appeared sharp growth and their peak around the 1830s was followed by a long decline, as other modes took over, until a revival in modern times. 
Why build a canal? Funded by the government to stem emigration by improving agriculture, fisheries and manufactures., the Caledonian threaded together four lochs to link the Atlantic with the Moray Firth, and while never fulfilling original promise remained busy with leisure traffic. The Crinan offering a short cut for fishing fleets, commercial sailing and puffers between the Clyde and the Inner Hebrides was supported by the Duke of Argyll. The Forth & Clyde was linked by a series of locks to the Union, that carried mainly domestic coal, building materials and, until coming of the railways, passengers between Glasgow and Edinburgh on so-called swift boats that offered "unparalleled cheapness" but took seven hours. With industrial decline, closure came in 1933 and the locks were soon filled in : the Forth & Clyde's navigation rights were extinguished in 1963, and much noxious debris accumulated whose residual presence requires continued monitoring.
Regeneration in this century by the Millennium Link required 7 opening bridges, 28 new road bridges, 9 new locks constructed, 32 locks and 38 masonry bridges refurbished, 5 km of new canal (notably at Wester Hailes) and removal of 36 obstructions and of 300k tonnes of silt. Sheet piling was used to protect the historic wall behind which the canal-bed could be reconstructed. The lost locks were replaced by the Falkirk Wheel, a tourist attraction in its own right that had to respect the Antonine Wall and indirectly supports 80 jobs in the locality. At the western end of the Forth & Clyde, Bowling Harbour is also now a visitor destination, with a former railway viaduct on a cycle-route and its arches housing shops.
The Helix at Falkirk aims to improve management of water-meadows, and its Kelpies, the world’s largest equestrian statues designed by Andy Scott, are a test of drivers’ concentration on the adjoining M9. A new canal has been constructed with a swingbridge facilitating access for larger craft to Grangemouth.
Hosting creativity on an industrial scale, Speirs Locks in Glasgow demonstrate how the canalside environment can improve spiritual wellbeing. Redevelopment has yielded housing and artists’ studios with sculptures and a base for the National Theatre, Royal Conservatoire and Scottish Opera.  Sports facilities include wakeboarding, with paddle sports at the nearby site of the old Pinkston Power Station. Claypits Nature Reserve originally formed by digging clay to line the canal demonstrate the potential for rewilding, with careful protection of native species such as the moorhen, and at Stockingfield a bridge has recently been provided to restore connectivity lost when an arm of the Forth & Clyde was built for Lord Dundas.
The 140 miles of Scottish Canals include 560 moorings, 253 bridges, 815 tunnels, 90 locks, 19 reservoirs, 227 embankments, 104 properties, 74100 engineering structures and 5 lighthouses. Any list of the most notable structures would include Neptune's Staircase of locks at the southern end of the Caledonian and the mighty Avon Aqueduct on the Union. The organisation aims to transform our canals, excel at what we do, create new opportunities and respond to global challenges. Management aims at avoidance of major catastrophic failure, staff and visitor safety, operability and functionality.  Locks have progressed from manual through hydraulic to the latest electrical ones. A smart canal is one that aims to support flood management by creating capacity in anticipation of a storm so that it may absorb the additional rainfall. The threat posed by climate change could be seen in the August 2020 embankment failure near Polmont which damaged the Edinburgh & Glasgow Railway.
The canals today offer twenty-first century assets for transport (freight such as timber, green routes, active travel on towpaths) ; water (flood defence, water sales, pump storage capacity) ; and energy (renewables, including solar and water-source heat pumps, and utility corridors).  An eighteenth-century innovation that seemed eclipsed by nineteenth-century progress, and on the verge of extinction in the twentieth, has found itself at home in the priorities of the twenty-first.