sac

So, I've been diving for a couple of years and have logged 72 dives. I have always been comfortable underwater and can also perform decent freediving. When swimming in the sea for fun I'm ok with going down to 10 meters to explore and hold my breath for a minute, comfortably coming back up...

I'm using a Suunto Eon Core computer with the transmitter for several months by now. I noticed that it reports a very high SAC rate at the beginning of every dive. Sometimes, the initial SAC rate is as high as 80 l/min. I wonder what can be the reason for that? Here is an example of a pool...