The waiting cruise boat on the Seine could be seen clearly but, perplexingly, there was no obvious route down to board it from the embankment by the Eiffel Tower.

This was not for a Sky News team’s Champagne-fuelled sightseeing tour. We were attempting to show how, in July, a floating parade of athletes would be part of the most ambitious opening ceremony conceived by an Olympic city.

The concept is spectacular, but the scale of the security operation is daunting. And on this day back in March the biggest threat to a ceremony being held on water seemed to be… flooding. The quays were submerged and, it soon became apparent, inaccessible.

Little indicates this is an Olympics racing to the finish line, as the last of the permanent venues was completed months in advance.

On one recent visit we joined a final inspection of the Olympic Village in the Saint-Denis district. A peek under the beds confirmed that they really are made from cardboard – but they survived my weight for a demo video.

Everything comes back to protecting the athletes who will be sleeping in them; the Seine flows through the Olympic Village, where they will board more than 80 boats for the opening ceremony.

In our interview with Olympic Games Executive Director Christophe Dubi came a rare admission of alternative options for the ceremony they are so determined to preserve: “Plan B is reducing, adjusting.”

It is an issue we would revisit on further trips, particularly after France raised its terror threat to the highest level. In April, the French Government went public with concerns about a purported IS-linked threat to Champions League games.

Outside Paris Saint-Germain, we spoke to Patrice Evra, a former captain of the French football team. “I don’t think it’s only about Paris,” he said. “I think this world is unsafe.” It was an impromptu plea not to be scared off coming to the French capital for the Olympics – and realism about the threat.

With 100 days to go, we heard from the Team GB boss. Andy Anson went beyond the predictable, generic ­comments of sports administrators: he was “clearly concerned” about managing the risks to keep athletes safe.

It is not unusual to dwell this much on terror ahead of an Olympics and Paralympics, although Tokyo was more focused on health and safety. Gangs and guns were the Rio worry.

But the Paris Games will be staged in more dangerous times, with war raging in Ukraine – leading to Russia being banned from competing – and in the Middle East.

While many Parisians we encountered during reporting trips talked of fleeing the city to avoid the congestion and chaos during the Games, watching an extravaganza of sport is a welcome distraction for so many.

Attending the Team GB kit launch in Paris – and hearing from medal hopefuls about their Olympic dreams – reminded us why France is willing to expose itself to significant risks to stage the games for the third time.

Much of the world will focus on Paris for a few weeks, enjoying a spectacular platform for the passion of thousands of athletes. But be braced for political protests across venues, putting commentators on alert.

And there will be vocal groans from Parisians about gridlocked roads and, potentially, soaring heat rather than water levels on the Seine. How the turmoil is navigated will determine the success of the Olympics and Paralympics for Paris.

For Team GB, however, it will all come down to the place on the ­medals’ table. They only have to focus on reaching the podiums rather than ensuring that the pageantry on the Seine is smooth sailing.

Rob Harris is Sky News’s Sports ­Correspondent.