Royal fleet, white whale hunting and community chests.
Royal fleet shows up on your map as a ship icon with R, and chests lights up in blue. Here are some places where you might find whales:
White Whale Locations
638, 901 - North of Abaco Island 658, 831 - South east of Floridian penninsula 950, 547 - North east of Great Inagua 880, 427 - North of Tortuga, South of Great Inagua, East of Punta Guarico 677, 320 - South of Cumberland Bay
Also, it is beneficial to get friends who play AC4 to join you on UPlay as they can share locations. Search board for discussions where people share their user names.
Only found this out this morning. You have to go to www.acinitiates.com, login with your uplay ID and it pulls up info from all your registered AC games. Pick a mission and it starts tracking you in game.
There's a solo community event up atm, "Employee of the month" the goal is to do 30 single assassinations with the hidden blade. Looks like you can only have one active mission at a time.