Here we have the little known wonder of Angel Island known as The Grand Chasm. A short walk affords views from both rims, unlike that other thing in Arizona which requires much more effort and you can't see the Ocean from.
Careful of the edges as it is a growing erosion problem and you don't want to join the soil which has already eroded.
The cache is away from the steeper section of erosion, so it should be pretty safe for the kiddies.