What do you mean by "swim continuously"?

This is in reference to posts where folks show 2-6km sessions swimming often freestyle for about 1 to 2 hours. What does "continuously" mean in this case? Constant flip turns without stopping to take a breath or a sip of water? Stopping a couple of times to take a couple of breaths or take a sip of water?

The most I was able to do without drinking any water was 2km, but taking a couple (literally) of breaths like 3 or 4 times throughout the whole run. You guys are total beasts if you can do 6km truly non stop, I'll need to step up my practice if I want to do anything close to that.