Does anybody know any brand ultrasonic sensor that are more reliable than HC-SR04 or ping sensor?
You could enter "ultrasonic sensor waterproof" into your favorite internet search engine or on Amazon for a list of decent results.
I, recently, gave up on using ultrasonic sensors and switched to a TFMini for my distance object detect project. With the TFMini mounted to a servo, I get clean scans of an area with clean repeat signals using single trigger per servo position.
"ultrasonic sensor waterproof" mostly gives results for JSN SR04T which I made a big mistake buying that sensor.
It has minimum distance of 20cm and it is very unstable.
Thousands of others are also having a problem with this sensor
This other waterproof ultrasonic sensor has minimum distance of around 3cm and is completely sealed from all sides making it 100% waterproof.
TOF sensor TOF10120 is also another good option. Much more cheaper and compact than TFMini. (Small size ToF Laser Distance Sensor 5-180cm I2C/Serial Port Arduino RaspberryPi | eBay)