www.google.com
Enter a phrase like "mainstream surfers forums" and press enter.
You may want to bear in mind though that in the land of "mainstream" they don't actually refer to themselves as mainstream. Businesses generally classify themselves under their industry or the TYPE of business they are, you know, like telecommunications, advertising, ladies clothing, gambling, handbags and accessories etc and searching for surfers will probably find you a few links about surfing.
Hope this helps. Enjoy your break but don't stay away too long, GFY needs you to keep the business topics alive to keep the trolls and spammers at bay.