Military organisers estimated that 70,000 people attended a 'Meet the Forces' day in Cardiff Bay on Sunday, at the end of the Nato summit Wales week.
Police have hailed the security operation - the largest the UK has ever seen - as a success, with 31 arrests made in total.
World leaders including Barack Obama left Wales on Friday, praising Newport and Cardiff for a warm welcome.
Police have confirmed they made a total of 31 arrests during the NATO summit. They include five for aggravated trespass, two for assaulting a police officer, and two for making hoax bomb calls.
During the summit hundreds of peaceful protesters marched through Newport and Cardiff but the number of campaigners was lower than anticipated.
Assistant Chief Constable Chris Armitt was the events gold commander. At a news conference on Saturday he told journalists the operation had been a great success.
Top policeman at Nato Summit says stun grenades were destroyed an hour before they were set to explode in path of world leaders.
'Meet the Forces' day was a crowd puller on Sunday as warships open up their decks in Cardiff Bay following Nato summit.
The day began with a spectacular fly-past over Cardiff and Newport by Nato aircraft.