Energy Tanks are crucial for increasing Samus's maximum health, allowing her to withstand more damage. There are a total of 8 Energy Tanks scattered throughout Zebes. Each tank adds 99 units to your maximum energy. Collecting all of them will significantly boost your survivability, especially during boss fights and challenging areas.
Many Energy Tanks are hidden behind destructible blocks, in secret passages, or require specific power-ups to reach. It's recommended to revisit areas with new abilities to uncover these hidden tanks. For example, the High Jump Boots or Screw Attack often open up access to previously unreachable ledges. Always keep an eye on your map for suspicious areas or unexplored corners.