Communication is a fundamental human characteristic. We communicate face-to-face, through written word, pictures, over the telephone, and hand gestures. Even with all these ways of communicating the one method of communication that has always mystified me is the message in a bottle. There are plenty of amazing stories through history of people sending and receiving written messages through a bottle found on the shore or caught in fishing nets.

I wanted my own message in a bottle but with a twist. Being inspired by my fiancée, I set out to design my own digital message in bottle. It features a usb flash drive and can be made to either be found floating in the water, or sunk in the depths of the ocean for a scuba diver like myself to be found.

Step 1: Materials

Materials:

Bottle
Flash Drive - I used the Super Talent Pico-C for it's ability to be water resistant, small, and inexpensive
Wire
Eyelets
Cork
Instamorph
Silicone
Sand

Step 2: Remove Soda and Label

The easiest way to remove the label is to soak the bottle in hot water then peal it off. Use Goo Gone to remove the remaining adhesive.

Step 3: Fill With Sand

If you are planning on sinking your message in a bottle, fill it mostly with sand. One pound is enough to make it negatively buoyant. If you want to make it float, skip this step.

Step 4: Prep USB Drive

Wanting to present the flash drive in an easy to view manner, I decided to hang it vertically from the cork.

Take a length of wire and loop it through the eyelet and flash drive
Place the eyelet in a drill chuck
Slowly twist the wire
Cut off the tail end of wires
Screw the eyelet into the bottom of the cork
Copy whatever message you'd like onto your message in a bottle. Here is what mine had:
- Text Document:
  Good Day Diver! Congratulations! You have found one of three Digital Messages in a bottle!
  This has been designed and placed around Roatan Honduras by Troy Hawkins during the week of July 25 -31, 2015.
  A little about me. I love diving! I live in Utah USA and I have been a diver since 2008. I was originally certified in Okinawa Japan. I received my Divemaster certification at CoCo View Resort here on Roatan in February of 2014.
  I graduated in 2013 in Mechatronics Technology and hope to be graduated in Mechanical Engineering by 2017.
  I want to hear from you! I want to hear a little bit about you. If you could share who you are and what you love to do that would be great!
  The full write up on how this bottle was made can be found at https://www.instructables.com/id/Digital-Message-i...
  My profile can be found here: https://www.instructables.com/member/tomatoskins/
  Please take a look and I can't wait to hear from you!
Wrap with plastic to protect the flash drive from sand

Step 5: Insert Cork

Insert the cork into the bottle, using an f-clamp press the cork into place. Use proper safety measures as the bottle has a very small potential of breaking.

Step 6: Instamorph Cap

As an added measure to keep the bottle sealed and the cork in place, I added an Instamorph cap.

Heat Instamorph
Form cap
Using scissors, square the bottom of the cap
Once the Instamorph has cooled slightly, coat the inside with silicone
For an added measure, secure Instamorph cap with a zip-tie

Step 7: Attach Note

Attach an eye catching note asking passerbys to take the bottle home. I included my email on the note for an added measure asking the finder to contact me (has been edited from pictures).

Step 8: Parts for Pressure Test Rig

Back in March, I asked the community for some help to figure out a way to read the internal pressure of my bottle of Dr. Pepper. This is what I came up with from their help.

Parts:

Saddle Valve
1/4" all thread
Tubing
Hose clamps
Low pressure gauge
Bottle of soda to test

Step 9: Assemble Pressure Test Rig

Cut the gasket flat where it will contact the top of the bottle. Shape the all thread to fit around the bottle. Assemble the top half of the saddle valve. Bolt the saddle valve and plate to the all thread. Attach the pressure gauge.

Step 10: Test Soda Pressure

I was really surprised at the consistent pressure of the 3 bottles that I tested. They were all within one PSI from each other. Since the average internal pressure of the soda was 54 PSI, these bottles (not necessarily the Instamorph cap) should be able to withstand the pressure all the way down to 121 feet underwater at sea level.

The deepest I ended up taking them was 70 feet. There's not usually a lot of coral much deeper than that, and most divers are only certified for 60 feet anyway.

Step 11: Underwater Test

Not being sure of how secure my cap assembly was, I decided to test my bottle closer to home in case I needed to make any changes before I left to Honduras. I would hate to be 2200 miles from home and tools realizing that my project wasn't going to work.

Step 12: Disassembley

I wanted to inspect the bottle first hand to make sure that there was indeed no water leaking in. To disassemble remove the cap and cork. Look at how dry that cork is!

Step 13: Find Some Water

Find somewhere you'd like to leave your message in a bottle. I personally went to Roatan, Honduras to leave my messages

Step 14: Go for a Dive!

Find a nice sandy area to leave your bottles. Remember to bury them deep enough in the ocean as to protect them from surge and deep enough in the sand they don't move.

I placed three bottles while in Honduras: