PRASBURR Polar Bear Floating Pool Thermometer for Ice Bath with String

Water temperature is a water-care number as much as a comfort one: a tub that has warmed up over a sunny week is the one to test first. This PRASBURR is a plain analog thermometer, 7.5 in (19 cm) long, hanging under a float shaped like a polar bear in a swim ring. It reads in °F and °C, comes with a string and needs neither a battery nor daylight.

That last point is why it suits a covered tub. A solar thermometer needs light that a lid shuts out; this one can hang on a hook in a dim garage all week and read the same. The listing gives no accuracy figure and no lower limit, so use it to follow the trend from day to day rather than to argue over a degree.

Tip: Lower it in when the lid comes off and give it a couple of minutes before you read it – a thermometer that has been hanging in warm air needs time to come down to the water’s temperature.