
Like a rooftop garden in an overcrowded financial district, Toronto's Leslie Street Spit is an unexpected urban oasis whose narrow escape from development has brought marshes, lagoons and forests to the centre of Canada's largest city.

Jutting into Lake Ontario just minutes from the worst of Toronto traffic, the more formally named Tommy Thompson Park was created over 60 years ago by the dumping of dredged sand, concrete chunks and earth fill, expanding what was once just a thin strip of land in the city's busy harbour.

Before & After 21 Aug 1972 . Toronto, Canada. NASA/Mark Blinch 22 Aug 2015 . Toronto, Canada. NASA/Mark Blinch Before: Leslie Street Spit in 1972.

After: The same area is seen in 2015.

Story The dumping continues to this day. While development plans have threatened the spit from its early days, the passion of the cyclists, birders, hikers and naturalists who flock to the artificial peninsula every weekend has preserved the unlikely park and left nature to prevail. For some, the spit offers the best views out to the Great Lake and towards the city's soaring skyline. For others, the auto-free roads offer safe, serene cycling, running and roller-blading in a city whose streets are often clogged with cars.

For most, it offers a 5-km stretch of nature untamed by development: home or visiting spot to 300 species of birds and site of 500 hectares of pioneer plant life, cottonwood and poplar groves, grassy marshes and gravel beaches.

While trucks hauling concrete and earth from the city's construction sites ply the spit from Monday to Friday, the park is turned over to an eager public every weekend, when its main road and numerous winding paths beckon city residents. Admission is free.

More than 100,000 people visit annually, according to the Toronto and Regional Conservation Authority, which owns the land and bodies of water included in the park. Initially eyed for port-related facilities in the 1950s, the spit was opened to the public in the 1970s after a decrease in lake shipping made those early plans obsolete.

Video The spit of land has a diverse ecosystem, with a rugged eastern shoreline giving way to wildflower meadows in the middle sections and marshy lagoons on the western shore, beneath the city skyline. The gradual transformation from a lifeless pile of rubble to an urban wilderness means the Leslie Spit is never finished, an ever-changing and unmanicured parcel of water and land.

Cobble beaches are, upon closer examination, composed of red brick, concrete, and kitchen tile worn to colourful pebbles, with patches of rusting rebar and urban detritus piled nearby - unlovely to some, a gritty oasis to others. Colonies of gulls, terns, herons and cormorants nest along the beaches or in the groves, attracting binocular-toting enthusiasts at dawn. Late summer brings butterfly enthusiasts to the spit, while anglers fish from the park's shores and small bridges.