S.C.O.U.T. · Nearshore Ocean Monitoring Buoy

Background

The gap is affordable data from shallow, nearshore water.

Coral reefs are among the most threatened ecosystems on Earth, but the instruments used to monitor them cost tens of thousands of dollars and are often serviced only every few years. When we interviewed reef scientists, they pointed to the same gap: affordable measurements in the shallow nearshore water where satellite products lose accuracy.

S.C.O.U.T. is designed to run unattended, on battery power, low maintenance, and a modular sensor payload. The target system cost is under $5,000, the figure researchers gave as a practical ceiling.

What it measures

The signals S.C.O.U.T. records

One sensor per measurement sits below the buoy. The electronics stay sealed above the waterline, and readings are logged on board before transmission.

Signal 01

Water temperature

A digital thermometer provides the temperature record used to compute NOAA Coral Reef Watch thermal-stress metrics.

Signal 02

Turbidity

An optical sensor detects runoff, resuspension, and sediment plumes as changes relative to the site's baseline.

Signal 03

Reef soundscape

A hydrophone records the reef's acoustics on board. The audio is stored locally and retrieved by hand — never sent over the radio — then analysed for bioacoustic signs of reef health.

Signal 04

Battery & health

Battery state-of-health and daily minimum voltage track whether the battery power budget is holding up over a long deployment.

A platform

One buoy, several possible signals

The sensor payload is modular. Dissolved oxygen, light, chlorophyll, and reef soundscapes are on the roadmap. Coral-reef health is the first application, with others planned.

See the architecture

The environment

The nearshore zone

S.C.O.U.T. is built for shallow nearshore water. It is biodiverse and productive, and it is also where remote sensing is least accurate.

A sunlit shallow coral reef, Raja Ampat, Indonesia. — **Shallow reef**Sunlit nearshore water, S.C.O.U.T.'s habitat

A shallow coral reef flat just below the surface, Misool, Indonesia. — **Shallow reef flat**Corals just beneath the surface

A green sea turtle gliding over a shallow reef, Great Barrier Reef, Australia. — **Green turtle**A grazer over the shallow reef

A vivid soft-coral colony on a tropical reef. — **Coral colony**Where thermal stress is measured

A coral bommie swarming with reef fish, Mayotte. — **Coral bommie**A reef outcrop alive with fish

A clownfish in its host anemone on a reef, Raja Ampat, Indonesia. — **Anemonefish**A clownfish in its host anemone

Magenta elephant-ear sponges on a reef, Solomon Islands. — **Sponge garden**Elephant-ear sponges, Solomon Islands

A cloud of orange anthias over a coral outcrop, Red Sea. — **Anthias swarm**Reef fish over the coral, Red Sea

A kelp forest on the Great Southern Reef, Australia. — **Water column**Turbidity and light through the column

The open ocean surface from below. — **Open water**The open ocean beyond the shelf

Mechanical design

The buoy, drawn

CAD drawings by John Ryan Myrdal. The two printed floats, the electronics housing and its cap, and the turbidity-sensor housing, printed in PETG.

Engineering drawing, Electronics housing — Electronics housing

Engineering drawing, Electronics housing cap — Electronics housing cap

Engineering drawing, Turbidity sensor housing — Turbidity sensor housing

How it works

The data path

Sense

The buoy wakes about every 30 minutes, reads water temperature and battery voltage, samples turbidity less often, and returns to sleep.

Store

Each wake appends one row to an on-board CSV log, timestamped in UTC. Raw data never leaves the buoy: the full archive, audio included, stays in on-board storage and is retrieved by hand.

Transmit

Three times a day, at 00:10, 08:10 and 16:10 UTC, the buoy sends its latest reading to shore as a 44-byte packet over a 915 MHz LoRa link, roughly 2 km line of sight. No cellular service or internet is used at the buoy.

Publish

On shore, an ESP32-S3 base station receives each packet and forwards it over WiFi. The telemetry pipeline validates it, runs quality control and NOAA Coral Reef Watch thermal-stress metrics, and regenerates this dashboard, using only the Python standard library.

From the buoy

Current reef status

Sample data, simulated until the buoy is deployed. Span 2026-08-14 → 2026-09-12.

Open the dashboard

Bleaching alert

No Stress

Latest temp

26.5 °C

Completeness

100%

Turbidity events

123