In a large bowl, toss 7 cups sliced cucumber (don't peel) with 2 tablespoons of salt. Let sit for 15 minutes then squeeze water out or very briefly rinse. (Do NOT let soak for more than 15 minutes or it will make the pickles salty! I promise, I know what I am talking about. Yuck, salty sweet pickles.)
In a small bowl combine 2 cups sugar, 3/4 cups white vinegar, 1/4 cup water, and 1 tablspoon celery seeds (Note from Kari: I used 3/4 tsp celery salt). Add some sliced onion and green, yellow and red peppers (the peppers are optional; they make it "pretty" and colorful.)
Pour the sugar mixture over cucumbers and let sit on counter for 1-2 hours, stirring often. Scoop the cucumbers, onions and peppers into a sterilized jar and add vinegar mixture to cover. Keep refrigerated.