I'm doing my OW Checkout dives this weekend. 2 dives on Saturday and 2 on Sunday. How long do these dives take (I read somewhere around 20 minutes each) and are they more skill oriented or are they more dive oriented? For example, am I going to have to control my buoyancy while checking out whatever plant/animal life is like in the harbor or hover like I was taught during my pool sessions? Thanks in advance for the help!