The location of the lake is a fictional American resort town called Silent Hill (yes, I'm writing fanfic), which has yet to be given a specific position. The weather there is generally cold, and somewhat foggy. The lake is very large, and apparently very deep (a small passenger ferry reportedly disappeared some years ago).
In essence, I was wondering if I could include any seaweed-esque (or perhaps vaguely tendril-y) lake plants that could logically impair a person, thusly making it more difficult for them to swim.
Any help would be greatly appreciated. =)