It seemed every single person in Brisbane was on the banks of the Maiwar river on Saturday afternoon, settling in with beach chairs and eskies to get the best vantage point. It was Riverfire: a much-loved explosive display involving fireworks, fighter jets and helicopter acrobatics that several locals separately described to me as “the most Brisbane thing ever”. But back down on the water, a smaller, quieter and newer spectacle was also pootling along the Maiwar: the Brisbane Art Boat (Northshore, until 24 September), an interactive artwork returning for a second time as part of the Brisbane festival. Where last year’s Art Boat housed a cartoonish inflatable neon castle, this year’s artwork is almost the exact opposite: the Spheres is an elegant and ethereal stainless steel structure by Lindy Lee, the renowned sculptor and Brisbanite. It is incredibly striking – and just as appealing as last year’s colourful work, it seems, with Instagrammers competing with small children to crowd around it.