And many spectators could be forgiven for wondering what lies beneath the surface of the 33-acre Waterloo Lake.
The 60ft-deep former quarry was sunk and filled by soldiers returning from the Napoleonic Wars - thus its name.
Secret Leeds researcher Michele Olbison has uncovered many of the stories of the lake's past.
As the park became increasingly accessible to the public towards the end of the 19th century, a pleasure steamer was purchased to operate trips on the lake. The Maid of Athens was in service for several years, and its fate has not been confirmed - although it is strongly rumoured to have been sunk in the deepest section of the water.
In 1884, an engineer called Charles Algernon Parsons tested his rocket-powered torpedoes on the lake - an activity that would be unthinkable today.
Ordnance did cause a tragedy in the 1890s, when a lifeboat was brought to Roundhay from Southport to give a rescue demonstration. A mortar was fired to start the show under the supervision of the army, but it was accidentally directed into the 5,000-strong crowd, where it exploded and killed five people.
The famous escapologist Harry Houdini also appeared on the lake's shores, and was thrown into its depths wearing chains, only to emerge moments later, unbound.
In 1898, Leeds Corporation replaced the Maid of Athens with an electric pleasure craft called the Mary Gordon. She was in service on the lake until she was sold in 1923, and eventually ended up working the River Calder in Wakefield before being scrapped. A group of enthusiasts salvaged the boat and are currently restoring it.
On one tragic occasion, a soldier carrying full kit fell off the Mary Gordon and drowned.
One of the most fascinating chapters in the lake's history came in the 1930s, when war prompted police to announce a firearms amnesty. Over 300 guns and ammunition were then, bizarrely, dumped in the middle of the lake at night as part of an official police operation. This caused issues in 1998 when the lake was drained, and officers had to patrol the area to ensure souvenir hunters did not retrieve any of the weapons. In a twist to the tale, an unexploded World War Two bomb was found soon after in a house in Seacroft, and it was believed that this had originally come from the drained lake.