World Oceans Day celebrates the global ocean and calls attention to the importance of protecting the chemistry and creatures of this precious resource. We need a healthy ocean to maintain a healthy world. It takes many techniques to monitor the ocean's health. Oceangoing research vessels deploy instruments that measure conditions at a range of water depths. Tide gauges along the coasts detect changes in sea level — both short-term changes due to storms and tsunamis and long-term changes due to warming water and melting land ice. Critical information about the ocean comes from space-based observations. Robotic satellites orbiting hundreds of miles above Earth can monitor sea surface temperatures and the development of large storms. Digital images taken by crew members on the ISS are also important for ocean monitoring. The astronauts’…