I was re-reading the Secret Voyage of Sir Francis Drake and it mentions he buried provisions in a cove in S America expecting a return to the same hideaway to continue to plunder the Spanish. In general, what provisions would sailors bury that would be valuable but also worth the risk of losing? Along with the dangers of spoilage and rust, there isn't anything I can imagine that is worth burying. Is there any documentation out there that has a specific list of items? My google-foo has failed me. Many thanks for any answers.
Edit: Thanks for the answers. I really enjoyed both comments. I had no idea that meat could last that long without refrigeration. I remember reading a book about Magellan that made it seem like hunting was plentiful around there. I also like the idea of storing all excess repair parts, those seem like one of those "low risk-high reward" burial items I didn't think about.
My knowledge is from a slightly later period, but I'll give it a shot.
Fresh water for one thing. The casks of water would already be brackish part way through an overseas voyage (even going as far as British colonies in the New World sailing from England), but any fresh water is better than none, especially when adulterated with rum or other spirits. Likewise, small beer (beer with a very low alcohol content, drunk as an alternative to (often) suspect sources of water).
You also have to remember that any foodstuffs provided for long sea voyages would be prepared to survive that voyage. Meats would be heavily salted and have a shelf-life of up to seven years before spoiling. Any bread would be in the form of ship's biscuit, otherwise known as hardtack, which similarly has a long shelf-life (but would require that you knock the weevils and maggots out first before eating).
Other than that, I'm really at a loss. Perhaps items required for repairs on a return voyage (e.g. nails, rope, tar, pitch, etc.)? Hope I've been helpful in some small way.
Source: Lots of reading and practical lessons working at historic sites.
Not a sailor and not the exact same time, but Navy bureaucrat Samuel Pepys is known to have buried his stock of wine and Parmesan cheese to save it from the flames of the Great Fire of London in 1666. The blog Age of Sail has a few entries on provisions carried by British ships during this era.