Waterproof Ultrasonic Transducers

I am using right now the known HC-SR04 module for detecting objects.

For my project I would like to have the transceiver / receiver transducers to be water proof :

How do I connect and work with this things ?
Should I build my own circuit for getting the echo/trigger pins for this ?

Thanks !

Think I finally found the solution :

But any other tutorials will help , Thanks !

Hi, Where did you get waterproof sensors?

Automobiles use them; anyone know of a source?

You can search on e-bay, few options there. If you're looking for more reliable ones, with complete specification, this company offers a wide range of options: http://www.maxbotix.com/

musskopf:
You can search on e-bay, few options there. If you're looking for more reliable ones, with complete specification, this company offers a wide range of options: http://www.maxbotix.com/

The main problem with maxbotix is the prices 100$ for most simple sensor :

Another source I found If any one needs :

http://www.kerrywong.com/2011/01/22/a-sensitive-diy-ultrasonic-range-sensor/