What is the best way to host a scavenger hunt?

I'm looking to host a large pirate themed scavenger hunt for a non-profit charity. I am in Galveston, TX and would like to expect a couple hundred families to turn out. I was thinking about giving clues to locations found around town (i.e. the historical wooden tallship here in town.) where people could collect a card to prove they were there. All would probably end digging for the final ticket (treasure) at the beach. Are there any other ideas to this? This is my first time running anything like this. Is there anything else I should know? How should I determine the winner but keep people from speeding all around town. Perhaps for every location visited and ticket collected, you get an entry into a raffle? Let me know people! I can use all the advice I can get!!!

First off, make sure you advertise advertise advertise! and the prize that your giving away, make it something worthwhile. It would probably be best to have like a big tv or something as a prize, (of cousre, entering this contest should be like 5 bucks per person, or more so you can use some of the money you collect to buy this prize) and the rest of the money can go to charity. Like, the bigger the prize, the more money you should charge. (dont forget maybe a 2nd and 3rd place prizes too) but for each entry, you should charge some sort of cover fee to cover the price of your prizes + extra money to donate to your charity. When everything has been set and you have all the people involved, set up just as you plan, but make sure they take pictures of themselves AT those location as proof they were there. Collecting a card and having a picture as double assurance they made it to those places. The digging at the beach is a fun idea too, but make sure no one sees you before you do this, so bury your treasure box first there (and inside the treasure box it could be a piece of paper telling them to bring that piece of paper to you for the prize) and so forth. It would probably be most successful if you motivate people to find as soon as possible... and first family to bring it to you gets a prize, one prize per familiy... something to that extent. hope this gave you some help.