Does anyone have a suggestion for a Smartthings sensor that can be place under the water and transmit the temperature of lake water from -20 - 70 f? I live on a lake in Michigan and we would like to record and display this on our devices.
Most people use a probe sensor for this type of application. There’s no power unit in the probe sensor itself, it’s cabled to a separate device, which is what has the radio to communicate with smartthings. This allows you to keep the cost way down compared to something with a radio designed to actually operate underwater. Typically a ds18b20 sensor is used.
You can see examples of some of these that work with smartthings in the following thread.