[distance 2D][0.4m - 20m][air/water][technology choice?]

Hi guys,

I am building a robot but I m stuck when I am calculating the distance between the Arduino and a beacon attach on something, the distance between the beacon and the arduino can goes from 0.4 meters to 20 meters let s say with 0.40 meters error accceptable for the accuracy I need.

My issue is that I am not capable to find the good orientation for this part of my robot due to the fact it can be underwater or not:

BLE seems not accurate due to the field of application. Knowing that I aldready use 433MHZ network to send other data from my arduino elsewhere on the ground.

Do you guys have any clue of what technology should I use to solve my problem?

You will need different technologies for air versus water.

For air, laser distance sensors like the LIDAR-Lite work very well -- 40 meters or more range with +/- 2.5 cm accuracy.

For water, sonar works well.