There are multiple ways of activating urban waterways, including those focusing on ecological, economic, and social aspects. Urban surfing is a unique way to use waterways in the city for recreation and people-watching, expanding on the use of swimming and boating by modifying the flows of existing rivers or creating artificial waves in waterways. Recently, a few examples of these projects came across my screens, and I was blown away.
Eisbachwelle | Munich, Germany
The most well-known of these urban surf spots is the Eisbachwelle, a standing wave created in the Eisbach River in Munich. According to the article “Eisbach: the mother of all river waves.” (Surfer Today), the site has been surfed since the 1970s, and over time the flow has been modified using planks and ropes to make the swell more consistent. The site hosts surfing competitions and as seen below, all season surfing in the urban core.

A video with more information about the Eisbach is featured in the Vans ‘Weird Waves” series.
Rif010 Urban Surf | Rotterdam, Netherlands
A more recent example that is opening soon, featured in the article “How Rotterdam built a wave pool for surfing inside a centuries-old canal.” (Fast Company, 06.04.24) outlines the plans for the Rif010, billed on the site as the “…world firsts surf pool in the middle of a city.”

The article delves more into the process of how the park was developed, and what was done to integrate the recirculating system into an existing canal. The project aims to be a destination, with different experiences for beginners to learn, versus areas for seasoned surfers. The club also includes a restaurant and bar, rentals, and several other amenities beyond the surf.
The proposed system, set to open soon after a 12-year process to get it built, produces waves every seven seconds through a complicated mechanical system of pumps, designed by consultants at SurfLoch. According to the article, Rif010:
“…uses pneumatic technology to mirror the way waves form in the ocean. At RIF010, this technology is powered by eight engines that are powered by wind energy sourced from the North Sea. The engines do what the wind does in real life, namely “push and pull” the water to create a succession of waves known as a swell.”
In the United States, a little bit of searching on on the topic yields the story of Big Surf in the 1960s. As noted in the article, “Big Surf: the story of America's first modern wave pool.” (Surfer Today) discusses the design and development of Big Surf, a totally artificial wave park in Tempe Arizona, simulating real wave action miles from the ocean.

Our focus here is less on the water park model and more on activating urban rivers and waterways. The article “River Surfing: The 7 Best Destinations in the USA.” (American Surf Magazine, 04.03.24) showcases several other examples worth a look, a few of which are more urban and river-based versions.
River Run Park | Sheridan, Colorado
Located near Denver, along the South Platte River, River Run Park was constructed with three surfing waves, called Chichlets (seen below), Benihanas, and Nikki Sixx, each providing more difficulty.

A plan shows the constriction of the river which were originally drop structures in a channelized stream. As noted in the ASLA Colorado award submittal from DHM Design: “The project reconstructed two large, existing drop structures and replaced them with six lower drop structures that include recreational features from wave shapers for surfing and kayaks to water shoots for kids play.”

Bend Whitewater Park | Bend, Oregon
Closer to (my) home, the Bend Whitewater Park provides multiple experiences through modification of the hydrology of the Deschutes River. There are 3 distinct channels, one focused on habitat, another for slow floating, and a third, a whitewater channel with multiple waves for surfing, kayaking, and paddleboarding.

This video from The Register-Guard shows the part in action.
The list above is not exhaustive (please send me others you know about), but gives a snapshot of some European and US places that provide unique opportunities to carve some waves without a trip to the beach. While not focused on the ecological benefits these provide special locations for use of urban waterways for surfers and spectators.
For some bonus reading, the article “A brief history of artificial wave pools.” (Surfer Today) outlines the historical evolution of introducing waves into water bodies through artificial means, dating back to the mid-19th century! It's probably worth a follow-up on this interesting tangent to the potential of waterway transformation.