Part of the Atlantic Intracoastal Waterway, the approximately seven-mile-long canal traverses the narrow neck of land joining Cape Cod to the state's mainland. Most of its length follows tidal rivers widened to 480 feet and deepened to 32 feet at mean low water, shaving 135 miles off the journey around the Cape for its approximately 14,000 annual users.
Most of the canal is located in Bourne, Massachusetts, but its northeastern terminus is in the town of Sandwich. Scusset Beach State Reservation lies near the canal's north entrance, the Massachusetts Maritime Academy near its south. A swift running current changes direction every six hours and can reach 5.2 miles per hour during the receding ebb tide. The waterway is maintained by the United States Army Corps of Engineers and has no toll fees. It is spanned by the Cape Cod Canal Railroad Bridge and two highway bridges—the Bourne and the Sagamore. Traffic lights at either end govern the approach of vessels over 65 feet.
Although being an artificial waterway, the canal is occasionally used by whales and dolphins including endangered North Atlantic right whales and can cause closure of the canal.
The idea of constructing such a canal was first considered by Miles Standish of the Plymouth Colony in 1623, and Pilgrims scouted the low-lying stretch of land between the Manomet and the Scusset rivers for potential routes. William Bradford established the Aptucxet Trading Post in 1627 at the portage between the rivers. Trade with the Native Americans of Narragansett Bay and the Dutch of New Netherland prospered and was a major factor enabling the Pilgrims to pay off their indebtedness. In 1697 the General Court of Massachusetts considered the first formal proposal to build the canal, but apparently took no action. In 1717, a canal called Jeremiah's Gutter was created in Orleans, spanning a narrower portion of the Cape some distance to the east, although it only remained active until the late 1800s. More energetic planning with surveys took place repeatedly in 1776 (by George Washington), 1791, 1803, 1818, 1824–1830, and 1860. None of these efforts came to fruition. The first attempts at actually building a canal did not take place until the late 19th century; earlier planners either ran out of money or were overwhelmed by the project's size.
The engineers finally decided which route through the hillsides to take by connecting and widening the Manomet and Scusset Rivers.
On June 22, 1909, construction finally began for a working canal under the direction of August Belmont, Jr.'s Boston, Cape Cod & New York Canal Company, using designs by engineer William Barclay Parsons. There were many problems that the engineers of the canal encountered. One was mammoth boulders left by the retreat of Ice Age glaciers. Divers were hired to blow them up, but the effort slowed dredging. Another problem was cold winter storms, which forced the engineers to stop dredging altogether and wait for spring. Nevertheless, the canal opened, on a limited basis, on July 29, 1914, and it was completed in 1916. The privately owned toll canal had a maximum width of 100 feet (30 m), a maximum depth of 25 feet (7.6 m), and took a somewhat difficult route from Phinney Harbor at the head of Buzzards Bay. Due to the narrow channel and navigation difficulty, several accidents occurred which limited traffic and tarnished the canal's reputation. As a result, despite shortening the trade route from New York City to Boston by 62 miles (100 km), toll revenues failed to meet investors' expectations.
A Kaiserliche Marine U-boat, U-156, surfaced three miles (4.8 km) off Orleans, on July 21, 1918, and shelled the tug Perth Amboy and her string of four barges. The Director General of the United States Railroad Administration took over jurisdiction and operation of the canal four days later under a presidential proclamation. The United States Army Corps of Engineers re-dredged the channel to 25 feet (7.6 m) deep while it remained under government control until 1920. In 1928, the government purchased the canal for use as a free public waterway. The purchase price was $11,400,000, and $21,000,000 was spent between 1935 and 1940 increasing the canal's width to 480 feet (150 m), and its depth to 32 feet (9.8 m). As a result, the canal became the widest sea level canal of its time. The southern entrance to the canal was rebuilt for direct access from Buzzards Bay rather than through Phinney Harbor. Before construction began, the Massachusetts Institute of Technology built a huge scale model (9 feet to a mile, roughly 1⁄587 actual size) of the canal to study the hydraulic effects of tidal currents on the enlarged and re-routed canal.
During World War II, shipping again used the canal to avoid Kriegsmarine U-boats patrolling offshore. The canal was protected by the emplacement of coastal artillery batteries at the Sagamore Hill Military Reservation at the northern entrance and the Butler Point Military Reservation at the southern entrance. The artillery was never fired in defense of the canal.
The Mystic Steamship Company's collier Stephen R. Jones was grounded and sank in the canal on June 28, 1942. Shipping was routed around Cape Cod, and one diverted ship, the SS Alexander Macomb, was torpedoed on July 3 with the loss of 10 lives. The canal reopened on July 31, after the wrecked Stephen R. Jones was removed with the help of 17 tons of dynamite.
The canal is used extensively by recreational and commercial vessels.
Service roads on both sides of the canal provide access for fishing and are heavily used by in-line skaters, bicyclists and walkers. Several parking areas are maintained at access points. People often just sit and watch ships and boats transiting the canal. Bourne Scenic Park is leased by the Corps of Engineers to the Town of Bourne Recreation Authority for use as a tent and RV campground adjacent to the Canal.
The Army Corps of Engineers maintains the Cape Cod Canal Visitor Center which introduces visitors to the history, features, and operation of the canal. Features include a retired 41-foot (12 m) US Army Corps of Engineers patrol boat, a 46-seat theater showing continuous DVD presentations on canal history, canal flora and fauna, real time radar and camera images of the waterway as well as a variety of interactive exhibits. Corps Park Rangers staff the center and provide free public programs on a variety of subjects. Tide charts, canal guides and brochures are also available. The Visitor Center is open seasonally from May to October, and admission is free. It is located on Moffitt Drive in Sandwich near the canal's east end. A second seasonally staffed center is at the Herring Run along Scenic Highway.
Scusset Beach State Reservation lies just north of the east end of the canal and offers beach facilities as well as tent and RV camping. A 0.7-mile (1.1 km) trail there leads to Sagamore Hill—once a Native American Indian meeting ground and later the site of a World War II coastal fortification with a view of Cape Cod Bay.
Bournedale Hills Trail extends 1.4 miles (2.3 km) along the north side of the Canal from Bourne Scenic Park campground to the Herring Run. The trail includes a 0.8-mile (1.3 km) self-guided loop which interprets the Canal's historic and natural features.