Women sweep the gold this year, with Mariko Mori and Adriana Varejão both introducing two stunning, large-scale installations. Incidentally, both also center on water. Over five years in the making, Mori’s Ring: One with Nature sets a luminous acrylic ring at the peak of the 190-foot-tall Véu da Noiva waterfall in Cunhambebe State Park. An amped-up version of the ring she installed at her past exhibition at New York’s Japan Society, this 10-foot-wide hoop changes color from gentle blue to gold as the sun strikes it at various times of the day. It is a simple but enchanting work that successfully evokes a message of oneness with nature and, echoing the five-ringed symbol of the Olympic Games, reminds of the interconnectedness of individuals across the world. That message will remain past the Games’ end, as the installation is a permanent addition to the natural environment.