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Hydrothermal Vent Experiment

Hydrothermal vents are only found in the deep sea, but you can replicate one at home with a few materials and a simple experiment!

You can think of hydrothermal vents like deep-sea geysers! They occur when tectonic plates in the Earth's crust shift, spread apart and create openings in the ocean floor. Hot magma from the Earth's mantle rises to fill these openings and create new crust, and cold water from the ocean seeps down into the openings. This cold ocean water circulates deep in the crust and becomes heated by hot magma. Pressure begins to build and as the water heats up, it dissolves minerals and becomes nutrient-rich. Warmer water is more buoyant and begins to rise. The hot water eventually exits the ocean floor; when it mixes with cold seawater, the minerals in the water cool and solidify, creating plumes of "smoke" in the deep ocean that can reach temperatures of over 700 degrees Fahrenheit!

With the experiment below, you can replicate a hydrothermal vent—without the extreme temperatures!


  • One large glass container
  • One small bottle
  • Food coloring
  • A piece of string
  • Hot and cold water


  1. Fill the large glass container with very cold water.
  2. Tie one end of the string around the neck of the small bottle.
  3. Fill the small bottle with hot water and add a few drops of food coloring.
  4. Keeping the small bottle upright, carefully lower it into the glass container until it rests on the bottom.
  5. Watch what happens!

If you're looking for creative ways to fill these at-home days, we have some kid-friendly, National Aquarium-approved ideas for crafts and activities that use upcycled and recycled materials.

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