May 22, 2026

Hydro Drop Rigs

by Thomas Rex Beverly

PROOF OF CONCEPT (Hawaii)

I've wanted to do hydro drop rigs for a long time. I finally (barely) got some to work.
These Gladys hydro drop rigs were designed by Jules Ryckebusch for the specific needs of my Hawaii and French Polynesia recording expeditions.
I got a two hydro drop rigs to work in Hawaii, but I destroyed a ton of gear in the process, because this was a highly risky design that was just supposed to be a proof of concept. But luckily the microSD cards survived.
That said, I'm still developing systems for hydro drop rigs and I would NOT recommend trying this design as a hydro drop rig that you leave on the ocean floor for 12-24 hours. Basically I destroyed a $2500 worth of gear to get 72 hours of hydro drop rig recordings. Yikes.
That said, this rig does work well as a hydro snorkeling rig! Seem more below.

Zoom F3 + SmallRig NP-F970 + Pelican M50 case + Gladys x2 = Hydro Drop Rig
You take a small Pelican Micro M50 case, cut a hole in the side, put the cables through, and then reseal with epoxy.
I used fishing weights, paracord, and foam pipe insulation (as floats). Watch the first video to see how that was rigged underwater.
An F3 and battery will barely fit inside that case (with some shell-less XLR inputs).
The main issue with this setup is that the Pelican M50 case is only rate for 1 meter (for 30 minutes). Jules and I though it could survive long than that, so I left it underwater for 24-48 hours at depths of 3-5 meters.
I had two of these hydro drop rigs in Hawaii. To my surprise the Pelicans only developed slow (but not catastrophic) leaks and the F3 recorded for most of the session. And the microSD card survived! All that gear was destroyed to capture the soundscapes for AMB94 Hawaii: Coral Reefs

The Pelican M50 case is a much better system for snorkeling. Then you can keep the case at the surface of the water while swimming and it doesn't leak!
The key is to take 2 selfie sticks and mount them to the case (with electrical tape). Extend the sticks and then hang the hydros down about 2 meters apart.
You're hearing high frequency snapping shrimp, and these little black fish that click their teeth to make the lower frequency thumps.
The recordings below were made in October 2025 on the island of Moorea in French Polynesia.

If you breathe super quiet and shallow through your snorkel it won't get picked up in the recording (if there is enough going on in the ambience). However, this is hard to do.
I realized that I could use a piece of paracord and let the rig drift away from me about 5 meters. Then it wouldn't pick up my breathing, but I could hold it in place above the reef fish that were clicking their teeth.
The whole rig also floats, so you can let it drift in the current and then swim after it.