There are 22 Buried chests, some of the maps are only unlocked in the Kenway's Fleet. You will need this treasures cause some maps allow you to do the MAX. upgrade in the Jackdaw.
TIMELINE:
1- Havana ( Queen Anne's Figurehead ) 0:14
2- Nassau ( Grey Sails ) 1:20
3- Salt Lagoon ( Money ) 2:26
4- Tulum ( Money ) 3:24
5- Abaco Island ( Money ) 4:25
6- Pricipe ( Money ) 5:27
7- Kingston ( Blackwood Wheel ) 6:25
8- Cayman Sound ( Money ) 7:33
9- Mantazas ( Elite Mortar Storage ) 8:30
10- Ambergris Key ( Money ) 9:37
11- Jiguey ( Money ) 12:08
12- Lone Bay ( Money ) 13:26
13- New Bone ( Money ) 14:15
14- San Juan ( Elite Elite Fire Barrel ) 15:11
15- Pinos Isle ( Aquilas Wheel ) 17:42
16- Andreas Island ( Elite Harpoon ) 18:43
17- Petite Caverne ( Elite Heavy Shot Storage ) 19:47
18- Cumberland Bay ( Money ) 21:20
19- Isla Providencia ( Elite Fire Barrel Storage ) 22:17
20- Cape Bonavista ( Money ) 23:12
21- Misteriosa ( Elite Heavy Shot ) 24:22
22- Anotto Bay ( Money ) 26:09