Hydrophone (Underwater Microphone) Kit

  • Sale
  • $ 40.00

Ages: 10+
Time to assemble: 30 minutes (no soldering required!)

Build your own hydrophone - an underwater microphone that can detect sound waves under water. Listen to the calls of marine animals, boat traffic, or if your pool is leaking. It can be used at your local fishing hole, a river, lake or even an ocean.

Learn how Shah Selbe used this hydrophone during his National Geographic adventures in the Okavango Delta in Botswana.

Inside the Basic Kit

  • 2 Piezo elements (1 as backup)
  • 1 PVC pipe brushing
  • 1 liquid tight cord grip
  • 1 25-ft speaker cable
  • 1 roll electrical tape
  • 1 foam bumper
  • 1 instant mix epoxy
  • Latex gloves

Inside the Premium Kit

  • 1 Amplifier* (may not be exactly as shown)
  • 2 Piezo elements (1 as backup)
  • 1 PVC pipe brushing
  • 1 liquid tight cord grip
  • 1 25-ft stereo cord
  • 1 roll electrical tape
  • 1 foam bumper
  • 1 instant mix epoxy
  • Latex gloves

*Amplifier -  includes a microphone input and a speaker/earphone jack. Comes with 9-volt battery.

What are hydrophones used for?

Did you know that hydrophones used to be the only way to detect submarines? They’re also used to listen for the calls of marine animals, like dolphins and whales, and can be used to map very deep waters. They help us listen for boat traffic, figure out whether undersea pipelines are leaking, and understand if and how underwater noise is affecting sea life.

What can you do with this kit?

Here are some of the exciting uses of this versatile piece of equipment. Let your imagination go wild.

  • Underwater bio-acoustics - what do the animals that live in your local pond, lake, river, estuary or ocean sound like? Listen for them swimming, eating, or paddling around.
  • With your hydrophone, you can collect underwater sounds using a recording device and software like Audacity and then upload the sounds to Soundcloud to share with other hydrophone enthusiasts.
  • Discover what a dripping faucet sounds like in the bathtub
  • Stick it in ice (or better yet a lake covered in ice)
  • What does CO2 sound like? Stick it in your favorite soda drink to find out
  • Helpful at home - listen to find out if your pool is leaking
This hydrophone is capable of recording low (10-500 Hz) and medium (500-15,000 Hz) frequency sounds. It was designed and tested at a depth of 25 feet but has been used successfully at a depth of 50 feet.


Sound wave frequencies can be divided in to three categories: low (10-500 Hz), medium (500-25,000Hz), and high (>25,000 Hz). For reference, fish hear sound frequencies between 500 to 1000 Hertz (Hz), some species up to 5000 Hz, a range within the low and medium frequency band. Low frequency sounds, such as noise from cargo ships and/or seismic exploration propagate long distances and experience low levels of attenuation, while high frequency sounds such as breaking waves or rainfall propagate short distances and experience high levels of attenuation. Therefore, low frequency sounds affect greater areas of the ocean over longer periods of time relative to high frequency sounds that affect smaller, localized areas for shorter periods of time.


Hydrophones utilizing a piezo-element are commonly employed for data collection. Piezo-elements convert a pressure wave in to an electrical signal which is then amplified and recorded through external recording devices for later analysis.

Research was done to compare commercial grade hydrophones (thousands of dollars) to this piezo-element design. Read the study.

How to become a Citizen Scientist

A citizen scientist is a person, like you, who has an interest in science and is willing to contribute time, ingenuity and creativity so that we can all understand our world a little bit better. If we all add our observations together, we’ll get a clearer picture of what’s happening in our environment --on land, sea and air.

 Warning - Choking Hazard

Not for children under 3 yrs

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