ANNAPOLIS, Maryland. — With a crisp salute to his predecessorAdm. Jon Greenert, Adm. John Richardson completed his 33-year rise to the Navy's top post Friday in a ceremony at the U.S. Naval Academy, assuming command as the 31st the role of chief of naval operations.

Richardson, a decorated submarine leader and recipient of the Navy's top most prestigious command leadership award, became the 31st CNO at a ceremony at his alma mater, the Naval Academy. Richardson takes 2:15 p.m., taking the helm of a service facing a myriad of challenges, including a loomingcoming budget crunch and relentless demand for Navy forces overseas.

In his comments, Richardson acknowledged the challenges on the horizon for the Navy, alluding to growing maritime powers like China. the Navy's growing competitor on the seas: China.

"I think that deep in our guts we sense a shift in the world, and we sense that once again it will be vitally important to protect our interests on the seas," Richardson told the crowd of hundreds, including 4-star fellow service chiefs. "Things are changing. There are regions and countries that are growing, economic centers of gravity that are shifting.

"And as it has been forever, when nations become strong enough to have global ambitions, it is only a matter of time before they turn to the sea to enhance their prosperity and their security."

Richardson characterized the world situation as "sporty," and said it was more important than ever for the fleetNavy to be forward — one of the tenets of the outgoing CNO, Adm. Jon Greenert.

Navy Secretary Ray Mabus told the audience that  was confident Richardson is up to the taskwas up for the job, noting the multiple collateral duties he's heaped on him over the years: from which include appointing him lead investigator into the 2013 Navy Yard shootings to in 2013:to the Navy's leading authority to deal punishment and disciplining to flag officers caught up in the "Fat Leonard" bribery scandal, the Navy’s largest in decades.

"No matter how hard the task, he was always up to it with calm professionalism," Mabus said. "Try as I could, I could not find a task that could defeat or discourage John Richardson. I am confident that John Richardson is ready for whatever faces him and our country."

Mabus praised Greenert's heart for the the men and women of the Navy.

"He's been a fierce advocate for sailors, filling gaps at sea, expanding opportunities for education, and leading efforts to integrate women in subs and into special warfare," Mabus said.

The ceremony, held in the academy's basketball stadium, was attended by hundreds of enlisted, officers, and foreign dignitaries. Among those in attendance were Defense Secretary Ash Carter, Chairman of the Joint Chiefs Army Gen. Martin Dempsey, Marine Corps Commandant Gen. Joe Dunford, U.S. Northern Command boss Adm. Bill Gortney, Vice Chief of Naval Operations Adm. Michelle Howard, Pacific Fleet Commander Adm. Scott Swift, Fleet Forces Command head Adm. Phil Davidson, and others.

Greenert, who will retires Oct. 1, was seemingly the happiest and most upbeat person in the room. The 1975 academy grad He entered the stadiumroom grinning. He joked and his high spirits and energy wereas on display during his remarks, where he laughed and joked with the crowd about selling a five-disk DVD set of all 750 of his public speeches made over the past four years for the low price of $19.99.

Greenert kept his remarks brief, thanking his friends and family and reflecting on what he'd learned as CNO during a turbulent four years. He noted his turbulent tenure, but said he wouldn’t have wanted to be anywhere.

"When I took watch there were storm clouds on the horizon," he said. "But the best place to be in storm is on the bridge, where you can see what's coming."

Greenert and Richardson both commanded the attack submarine Honolulu, a fact that Richardson noted in his remarks, saying that one of his great qualifications is that he had "become an expert at following Adm. Greenert."