The freshwater forest by Michel Roggo, Switzerland. Slender stems of Eurasian watermilfoil, bearing whorls of soft, feathery leaves, reach for the sky from the bed of Lake Neuchâtel, Switzerland. Michel has photographed freshwater regions worldwide, but this was the first time he had dived in the lake nearest to his home. He was swimming near the surface –absorbed with the beauty of the plants and their small reddish flowers –when he spotted a huge pike disappearing into the mass of vegetation below. Very slowly, he sank down for a closer look. When he reached the bottom, he found himself immersed in an ‘underwater jungle with an endless view’. Watermilfoil is native to Europe, Asia and North Africa but has spread worldwide. It can grow from fragments and so is easily transported, rapidly colonizing ponds, lakes and slow-moving water, with dense growth that can shade out native species. When Michel inspected the stems, extending up several metres, he noticed that some supported thick clusters of zebra mussels. Originating in Russia and Ukraine, these small molluscs, with characteristic banding patterns, are prolific breeders that are spread by boats and have invaded most of western Europe and North America. Their filter‑feeding significantlyreduces plankton densities, increasing water clarity and disrupting ecosystems. Carefully manoeuvring his bulky diving gear in the tangle of vegetation, Michel composed his picture with a wide angle to convey the feeling of gazing up from a forest floor, among throngs of towering trees.