First off, it's not a bug, that's how the game is supposed to work, and you are bad and should feel bad for using the term "bug" incorrectly. But I see SixArt has already abused you over your choice of verbiage, and will doubtless insult and demean you further, so never mind that.
Specifically, drinking an energy drink before you go in the water will increase the amount of time you can swim to 45 seconds. This will still not be enough to fully explore the lake, and you cannot carry more than one energy drink at a time. So you will need to return to Dicks and purchase a drink, repeatedly, until you have gotten everything you need.