LakeTemp is a compact dock-mounted sensor that tracks surface water temperature hourly, all season. It clamps onto a dock post in minutes with no tools, uploads automatically over Wi-Fi or a base station, and runs all season on batteries.

At $150 it is the lowest-cost entry point in the Toolbox, and the readings are visible to the whole lake community rather than one household.

A monitoring subscription is available from $84/yr ($7/mo).