Most of our products do not measure distance, they measure time of flight. To convert this to a distance, we need to know how fast the signal was travelling. How well we need to know this, depends on our project tolerances.
We do not usually measure depth either, we measure pressure. There are lots of ways to convert pressure to depth and getting it wrong will affect your final position.
With this in mind, Fusion 2 has a few options to keep your sound speed up to date, so you can choose the one most applicable to your work. We also cover the common pressure to depth formulae, if you want something else, you can write your own using the custom formula tool.
Watch this helpful video that will walk you though this process.