Mayan Stelaes are found throughout the Assassins Creed Black Flag world, there are 16 in total to collect and they offer a prize at the end of a set of Mayan armour with the ability to deflect any projectile aimed at the played. Pretty useful! Here is the list of all 16 Stelaes and where to find them. Take the stones to Tulum after completion.
#1 - CAT ISLAND (734, 694)
On top of a ridge overlooking the ocean.
#2 - GREAT INAGUA (845, 468)
Done during the mission “Old Cove”.
#3 - MISTERIOSA (303, 199)
In the middle of the island you will find some ruins. The Stelae is high on them.
#4 - MISTERIOSA (296, 196)
On the western shore of the island.
#5 - SANTANILLAS (217, 245)
Next to some huge rocks in the centre of the island.
#6 - SANTANILLAS (221, 242)
On the southern part of the island, on top of a huge rock.
#7 - TULUM (70, 405)
On top of a Mayan ruin in the north of the island.
#8 - CAPE BONAVISTA (179, 593)
In an area surrounded by waterfalls to the north of the Cape.
#9 - MATANZAS (343, 642)
In the eastern part of the island, within a swamp.
#10 - TORTUGA (875, 379)
On the beach where you dock The Jackdaw.
#11 - PINOS ISLE (334, 476)
In a field of pillars and ruins.
#12 - PINOS ISLE (342, 478)
On the north-eastern edge of the island.
#13 - NEW BONE (431, 116)
Just on the outside of the restricted area to the north-west of the island.
#14 - ISLA PROVIDENCIA (502, 44)
On top of ruins to the south-west.
#15 - ISLA PROVIDENCIA (502, 44)
The north inside of a restricted area.
#16 - LONG BAY (525, 253)
On the southern edge, behind the observatory.