More than 2000 people took the chance to explore and enjoy the new recreational space of Hope Valley Reservoir Reserve on the first day of its gates being opened to the public in almost 150 years.

Sunday morning's celebrations were highlighted by the First Wheels Across The Wall ride and walk launched by Minister for Environment and Water David Speirs to formally open the latest reservoir reserve in South Australia.

It was a spectacular sight with hundreds of people on foot and bicycle making their way across the 800m long dam wall with the spectacular backdrop of Adelaide's oldest operational reservoir and the hills in the background.

And the visitors kept coming, with the reserve open until 8pm.

Each day over summer, except for Christmas Day and in line with CFS Total Fire Ban advice, the reserve will be open from 7.30am to 8pm.

Hope Valley Reservoir Reserve is open for walking, running, cycling, picnicking and your chance to get back to nature and enjoy the benefits of wide open space, right in the heart of metropolitan Adelaide.

New trails in the reservoir reserve link with the existing network to create a loop of the reservoir, while also linking in to the popular O-Bahn Bike path to take riders and walkers all the way to the coast and up to Tea Tree Gully.