What would be the best way to make a treasure map?

I am planning a boating trip with several kids this summer and I am wondering how I could make a good treasure map and treasure box for ten year old kids?
My plan is to bury the treasure ahead of time and then give the kids the map and tell them to find the treasure and they have to jump off boat and swim ashore.
Much like I seen in a movie years ago call White Squall,, which is probably the best boating movie ever.
Thank you for your help!

Get really nice parchment from a craft store and stain it with tea. burn the edges a little.

Get a nice ink pen to draw the map. (the kind you fill yourself)

Try to come up with riddles to the next spot too. That would be fun.

♥Crazy bratz kidz:A quest to find treasure♥

Treasure Tracker $29.98 Hunt for coins, watches, jewelry and more with your very own Treasure Tracker digital metal detector! Explore the science behind searching for valuables at the beach or in your own backyard! You’ll be amazed what you can find buried right beneath you. Adjustable settings, a digital backlit display and audio tone alerts make this metal detector easy to use and provides hours of fun! You’ll never know when you could strike it rich!

Find It Sports Game $19.99 Find It is a totally contained 3-D Treasure Hunt. No batteries, buzzers, or beepers; just a good old-fashioned parlor game. The game is designed so that it can be left out on the coffee table, waiting room, desk as well as being the perfect travel game. Find It is a completely contained adventure;

Pirate Treasure Hunt $13.88 Set sail for adventures by creating your own message in a bottle! Hide bottles for a fun scavenger hunt or used them as invitations for a pirate themed party! Includes canvas treasure maps for kids to decorate and 5 bottles with corks and labels.

Pirate Treasure Chest $278 Hoist the anchor and unfurl the Jolly Roger! This collection sets the theme for adventure on the high seas and the search for buried treasure! Bold colors create a perfect background for inspiring images of ships at full sail, treasure chests, and mysterious maps where �X� marks the spot! Stylish wood add to the authentic detail! – Adult assembly required – Features spacious interior with dividers , saftey lid supports and cut-outs to prevent finger pinching

Tag Maps: USA $18.95 North, south, east, west—find an amazing interactive adventure with maps that take you from sea to shining sea, across continents and more with this map pack. Soar into an around the world adventure as you learn fun facts and play games with the two sided Tag World & United States maps. More than twenty interactive games bring fun characters and map facts to life. Teaches map skills, world & U.S. geography, famous places and animals and world languages. Meet kid characters from around the country, learn what they eat and how they play. Meet kid characters from around the world and learn how to say “hello” in their languages. Parents can follow their child’s play and learning progress on the LeapFrog Learning Path. Play in LeapWorld, a safe, online learning world with more games and rewards to expand the fun. Teaches: Map Skills Children develop map skills by reading and drawing maps of familiar places and then using maps to locate places, measure distances, and compare regions. North American Geography Geography refers to the study of the earth and its features, including the ordinal directions (north, south), physical characteristics (oceans and mountains) and the effects of human activity. World Languages Children can build on the foundation of their first language and enhance cognitive development by learning the sounds and words of another language. World Geography Children may begin by learning about people and animals from different regions and eventually use geography as a tool to also understand places, cultures, and the world in spatial terms.