Note that this cache is not at the posted coordinates. Solve the puzzle at the bottom to find the hide. Additional requirements for logging (see below) also apply.
Simple requirements prior to logging cache:
1) Log fifty total stars of difficulty on caches currently located on Treasure Island or Yerba Buena Island.
2) Log fifty total stars of terrain on caches currently located on Treasure Island or Yerba Buena Island.
3) Post your list of finds.
4) Find this cache and sign the log inside.
(Hopefully) Helpful clarifications:
1) Disabled caches do count toward your total.
2) Archived caches *do not count* (I lost a few myself in coming up with my list, so I'm sure it's possible without old finds). Keep this in mind if you post a list long before you find this cache.
3) Owned caches do count toward your total (hrc333 rule).
4) Once you've logged this cache, you've logged it. You will not lose your eligibility should some of your found caches be archived.
5) You are welcome to log it multiple times if you reach 50/50 again using *an entirely different set of finds*.
6) This cache will not count toward your 50/50.
Here is my (jeremiahsjohnson's) qualifying list of finds:
GC5D7DX Naval Station Treasure Island 2.5/1.5
GC56GKF ASoIaF: Eddard Stark 2.5/1.5
GCD018 What a Sight! 2/1
GC572C7 ASoIaF: Daenerys Targaryen 2/2.5
GC3WZ7P A Midsummer Night's Dream 3/1.5
GC5D5V6 Golden Gate International Expo: 1939 3.5/1.5
GC2HKEE Barnacle Bill's Haunted Hostel of Treasure Island 2/2.5
GCWDYZ Yerba Buena GeoCoin Integrity Test 2.5/4.5
GC5EYX0 Tower Jam 2/2
GC5EBDT Yerba Buena Kayak Recovery 2/4.5
GC4GQ6V Yerba Buena-Cable Ready 2/5
GCX2E0 Yerba Buena Kayak Cache 2/5
GC1PWPA Rimless Wagon Wheels 1.5/1.5
GC1DA6M Little League TOC 2/1.5
GC3RKB2 Boo Radley's Gifts 3.5/1.5
GC5D27E Sleeping Monkey 3/4.5
GC56ZX0 ASoIaF: The Night's Watch (A Night Cache) 4/3
GC205WV Naval Fire Fighting School 2/2
GC56WF6 Vultures 1/4
GC56G10 ASoIaF: Harrenhal 3/2.5
GC56EPN Earth Glass 4.5/2
GC56G0P ASoIaF: Damphair 2.5/3
Total Difficulty / Terrain 55/58.5
Note that it's possible to do this without finding any crayon boxes. Though they certainly will help.
As the main challenge here should be the find, we'll let the puzzle be mild:
The cache is approximately 544 feet from Barnacle Bill, 552 feet from Daenerys Targaryen, and 1551 feet from the Three-Eyed Crow. Visiting hours are sunlight to sunset.

You can validate your puzzle solution with certitude.
Note that difficulty and terrain ratings are based upon the overall challenge. The cache itself would be a 2/2.
Original cache contents include three unactivated trackables, one for each of the first three finders. Please take just one.
Note (11/1/14): updated Certitude hint in response to the first logged visit. Please re-solve for an updated hint. Also, a rule clarification (this cache won't count toward your 50/50) added above.