Enjoy watching One Piece 516 at TailedFox and read the following summary of the episode entitled "Luffy's Training Commences - 2 Years From Now at the Promised Place".
Jinbe left Luffy and the crew. Hancock is head over her heals in love with Luffy. Ordered to navigate to Rusakaina Island ship steers towards their new training ground, an island where seasons change weekly. Hancock promises to bring food to Luffy daily, but gets refused as no women are allowed to stay as Luffy train. Hancock is not taking this well, but Rayleigh calms her down by saying that this is in the best of interests for Luffy.
Luffy and Rayleigh are examining the training grounds. The Island of Rusakaina has hundreds of wild beasts, many much stronger than Luffy. Rusakaina is now a deserted island, but it wasn't always so. Country long ago evidently lost its civilization as they lost their will to live.
As Rayleigh started explaining Haki to Luffy, an huge elephant attacked Luffy. Luffy hurriedly used his Second Gear using his Gomu Gomu no Jet Pistol, but to no avail.
Rayleigh coolly continued his lecture on Haki. First lesson consisted of Observation Haki as Rayleigh felt the elephants presence and dodged each blow with ease. Then the Armament Haki finished the big elephant off the first time. Hard surface may make this defensive technique an offensive one. To demonstrate Rayleigh flickered one to Luffy's forehead. To Luffy's surprise he felt pain. When elephant came after them the second time, Rayleigh used power to intimidate, the Conqueror's Haki. This did the elephant in. Rayleigh explains though that using haki improperly can cause a lot of damage.
Rayleigh will train Luffy, teach him haki and other techniques, but he will be tough on Luffy. Luffy went to pick up his straw hat and Vivre card. He recalled promises, Sabo, and Ace made and began the two year training camp with Rayleigh.