Hey guys.   New to 5e and while I try to find a game to join to learn the ins and outs of 5e I have been building the setting I will use when I eventually start DMing.    I have an city that sits on a coastline.   It is the capitol of the Province.   In the city I wanted to make a Colosseum but make it be filled with water.  My thinking is it is part of the entertainment of the city like a local football stadium.   I was trying to come up with some battles / races / contests I could do that PCs could watch or compete in.  I'd love to crowdsource some ideas to make this happen.   Care to spitball some ideas together?

Kraken Fan #69

Have the collisium flooded, and floating bridges that are laid out like a maze of sorts. A goal at each end. Players need to place a ball into a goal. So they can run along the bridges and pass the ball.

The kicker would be they get no weapons, or maybe only certain play positions get weapons,  and the flooded water has nasty things, sharks, giant squid. The players with weapons can't make a goal but the can attack creatures in the water, maybe give them pikes or spears. The players without weapons can score a goal, and of course shove other players into the water.

Other ideas would be simar, flooding the coliseum and having gladiators,  or crimes guilt of murder or other terrible crimes have to fight sea monsters.

Have the coliseum flooded and battle-ships sail around in it and gladiators sail the ships and fight each other, like how they did in the actual coliseum. 

Have a bunch of large squid set loose in the flooded coliseum and contestants have to fight them and whoever kills the most wins.

There could be shows where powerful magicians move the water into complicated and beautiful shapes for the entertainment of those watching. They could also have trained sea creatures performing too.

Or just have gladiator fights with sea monsters in a flooded arena as a form of public execution and entertainment.

Pit fighting might be a good battle sport to have in the colosseum. There are rules for it in Xanathar's Guide to Everything.

You can also create sports and/or rules for them. They're mostly just skill challenges, and you can add in a couple of choices (such as "run ball" or "throw to wide receiver") if you want to allow some options for your players as opposed to just letting them roll.

The first adventure in Journeys Through the Radiant Citadel has some neat challenges/contests. They may not be exactly what you're looking for, but I would recommend checking them out if you already have the book.

Pit fighting is one of the activities I had in mind, but instead of on land, the colosseum is flooded and my brain is not giving me enough scenarios to make this viable at the moment.

Kraken Fan #69

If the colosseum is submerged in water, then you might want to have a very small space where there is a bit of land. That way, you don’t limit your selection of activities that much, and you can also add a “Don’t fall into the water” mechanic for some of the on land challenges such as pit fighting.

As for water sports, you might want to make a swimming race, or a challenge where characters have to defeat or avoid some sort of sea monsters.