Thirty years ago in Kolkata, India, catching sight of the South Asian River Dolphin (or Gangetic Dolphin) was a common occurrence. Yet over the decades, the rise of industrial pollution caused the water mammals to drift away from the city. Until nationwide lockdown, that is. With humans activities at a standstill under India-wide lockdown since late-March, water pollution has dramatically decreased -- and the dolphins have returned. Their population is estimated to be between 1,200 and 1,800.