The "Victoria's Chinatown" Adventure takes you to five locations around Victoria's historic Chinatown. Once you've completed all five stages of the Adventure, you'll be given the coordinates to this bonus cache. There's nothing at the posted coordinates, so you don't need to go swimming. This cache isn't in Chinatown, but is less than 10 minutes of walking from the end of the Adventure.
Instructions: After you've completed the Adventure, go back in to look at the journal and scroll to the last entry to get the coordinates.
You'll need to have the "Adventure Lab" app installed on a mobile device in order to complete the Adventure. Links to download the app from the Apple App Store or Google Play Store can be found here: Adventure Lab app
The Adventure can be accessed here: Victoria's Chinatown Adventure Lab