This is a four stage multi with a bit of fun along the way.
Stage one info: Make sure you get the GREEN light at this one. The RED light will have you swimming your way right back to stage one.
Stage two info: Typical hide, sit and take a break here while you complete your work. Be sure to hide better than you found it.
Stage three info: Take a look at the old logs from the archived cache here.
Final info: Be sure to sign the "log". If you wish to leave a longer note in the field please use the extra log there. This extra log is also from the original cache. Feel free to check out some of the messages left "back in the day".
Additional hints are spoilers!