Welcome to the Lake of the Ozarks! This should be a fun 3-stage multi. The first two stages will require some sort of watercraft--a boat, PWC, or a kayak (if you are happy paddling ~5 miles) will work just fine. Once you gather the information from Stage 1 you will be able to calculate the coordinates for Stage 2 and proceed by water to Stage 2. At Stage 2 you can calculate the final coordinates as shown below, but to get the final cache you will need to be back on dry land in a vehicle. Do not attempt to navigate directly from Stage 2 to the Final in your watercraft nor by jumping into the Lake, swimming to some spot on land and then making some long trek over land to the final. Not only doesn't that make sense here, you would not be able to do so without crossing private property.
Stage 1: Hopefully you've enjoyed your boat ride to Stage 1. Look to the east and you will see a large white sign with red letters. The coordinates for Stage 2 are:
N38 9.ABC W92 47.DED
A-E are mapped to particular letters on the sign (ignoring non-letter symbols):
A = 4th , B = 8th, C = 9th, D = 6th, E = 13th
Once you have the letters above, map them to numbers using your Phone keypad. You know, like when you have to dial 1-800-GOC-ACHE, how do you do it?
Stage 2: Hopefully you enjoyed your boat ride from Stage 1 to Stage 2. Looking west you should see a green sign with white numbers and letters. Let's use that to calculate the final cache coordinates. If each digit on the sign is labeled as D1, D2, etc. and each letter on the sign is labeled L1, L2, etc. and you map letters to numbers the usual way starting with A=1 (if the letter maps to a 2-digit number, sum the digits) the final coordinates are:
N38 L2.L1 L5-1 D2+1
W92 D1+1 D2.L3-1 L4 D2
Enjoy the rest of your boat trip and once you are off the Lake and on dry land head to the final cache. It's not that far from here by the crow!