This is a smart pool thermometer for all pools and bodies of water.
What else you need:
3D printing:
Print the pool_thermo_v2_base.stl and the pool_thermo_v2_hut.stl in their original size.
Software:
I recommend the ESP8266-HomeKit-Temperature-Humidity-Sensor software for IOS users (Link: https://github.com/AchimPieters/ESP8266-HomeKit-Temperature-Humidity-Sensor)
Direct link to the appropriate firmware: https://github.com/AchimPieters/ESP8266-HomeKit-Temperature-Humidity-Sensor/releases/download/0.0.4/dht11_gpio2.bin