Looking for ideas for a feast/festival set in a port city

They would have seaweed-wrapped rice balls and a variety of fried fish options for food.

There could be eating competitions, feats of strength (think the Scottish strong man competitions like carrying enormous rocks across a bridge, or picking up a log and throwing it for distance), classic carnival games like throwing rings around bottles. etc.

Maybe the carnival structures use fish/monster parts from the sea in their design.  Torches are lit with oil or blubber, the frames of tents may be monster ribs, etc.

Party-clothes may be carefully crafted clothes made of strung-together fish scales in gaudy patterns of bright colors.

And of course, the sea is only one side of scenery... the other side is land, so you can have all of the normal festival features (eating competitions, feats of strength, ring toss, etc). 

Are there any friendly aquatic races, such as Merfolk or Sea Elves, nearby? Imagine the party extending into both the city and the sea, land and sea folk mingling on the shore. 

Whenever there's a big celebration, I love the idea that the mirth and merriment causes a bit of a bleed-through effect between the Prime and the Feywild, and some Fey revelers show up to join the fun (and usually cause some chaos). This creates a neat adventure hook for the party while still maintaining the festive vibe. 

Maybe some eladrin have started to dominate the games lining the streets, or merry Fey hobgoblins are trying desperately to dance with people but everybody's afraid of them. Or maybe an Archfey shows up to really get that wrestling match exciting! 

Hot air balloons.

Jugglers. I love jugglers. I am a juggler. Juggling is awesome.

Clowns

Live performance by the hit band Leaden Balloon, The Tumbling Rocks, The Why, Bows n' Roses, Burgundy 6, The Smash, etc.

There has to be a swimming competition and a competition to hold your breath.

Perhaps a fishing contest for the biggest, or strangest fish.

Knot tying contest.

Special appearance by Hooty and the Blowfish. And Great White. Maybe Seal. Perhaps some Blue Oyster Cult?

Or if you want to go with a more D&D theme: Kelpie, Imagine Dragons, The Grateful Undead,, Glass Cannon, Deep Purple Worm, or The Secret Doors.

Quote from WilsonJ >>

There has to be a swimming competition and a competition to hold your breath.

Perhaps a fishing contest for the biggest, or strangest fish.

Knot tying contest.

Special appearance by Hooty and the Blowfish. And Great White. Maybe Seal. Perhaps some Blue Oyster Cult?

Or if you want to go with a more D&D theme: Kelpie, Imagine Dragons, The Grateful Undead,, Glass Cannon, Deep Purple Worm, or The Secret Doors.

 Nice. I can't believe I didn't think of the Blue Oyster Cult.

Imagine Sea Dragons?

Battle of the Bards--like Woodstock by the sea.  But with the possibility of introducing one or more plot hook NPCs to set up future adventures....

LIGHTSHOW!  Put a different color in the lighthouse and have it shine on the city.  A shimmering effect in front of the light that makes the city shimmer like water.

MUSIC!  A sea shanty competition. Seals & Croft, The Captain & Tenillle, Jefferson Starfish.

GAMES! Have a pearl in the oyster competition.  For 2gp they can shuck an oyster.  If they roll 99 or 100 on a d100 they can win a 500gp black pearl.  No pearl is fine, eat the oyster!  Roll another d100.  On a 01 or 02 they get poisoned with the red tide or something similar.

Racing up a ships mast to ring a bell.  A series of 3 successful (DC 15) acrobatics checks to make it to the top.  Keep track of how much they make the check by and total it up.  The highest number is the fastest.  The winners takes home a magical pole of angling.

A strongman competition where people hold their breath and pull a small craft by the anchor on the sea floor.  If they make a few Con Checks and Strength checks, they win a shiny jewel encrusted mother of pearl/abalone shell belt buckle worth 100gp.  A fail of a CON check (make them successively harder 10, 15, 20) means they have to surface.  Keep track of the Strength checks and total them up.  Highest total wins!

High dives from the lighthouse.  Harpoon toss.  

Here's some inspiration!

“Live performances by…”

Do you have a bard who’s sort of an inside joke repeating NPC in your campaign?  This is a chance to introduce one if not

maybe a festival of the sea

A festival where you and the other nearby friendly aquatic peoples celebrate the ocean and it's sailors/people/nautical heroes?

SO! I'm doing something very similar to I needed a festival, but the prompt is kinda like the movie the nutjob (ALl characters are small rodents, ect.) And you hvae given me a terrible idea, I am now writing sea shantied to the sound of remixed frog croaking. Thank you.

Here are some basic/minimal ideas:

• Parade - include the actual warriors who defeated the sahaugin, and have floats depicting the defeat of sahuagin at the lighthouse
• Music - bards performing songs about the battle of the sahuagin
• Magic: make use of divine and arcane (esp. illusion) magic in the celebrations

Make it be a bit to much so:

extends into the sea,

ocean highlands games,

light show,

sea shanty competition,

hot air balloons,

possible murder,

noise,

NPCs overwhelming the party with requests,

sea dragon dance show,

and parade

Surprised nobody's suggested the greased pole challenge yet. It's a staple in maritime shows in the UK.

A mast, probably 20-30ft. long, is laid down sticking out over the harbour, and greased up thoroughly. If you can balance across it to get to the end, then you win a prize. Based on the success rate in the real world, the DC should be pretty high. I'd suggest some sort of cumulative one - DC 20 for each 5ft, DC 15 to stay on the pole, and anything lower than 20 is added to the next DC.

So if they roll an 18, they stay on, but the DC's increase to 17 and 22, so however much below 22 they roll is added to the next DC. Roll consistently high, you get the prize - roll low, and you start to lose balance! 3 checks would do the job, I think - 4 would be too much!

Grilled food, mobs of seagulls (maybe an Aarokokra gang?), bright, spherical lights on strings, all the ships flying flags and decorated up, sailing-boat races, low-tide estuary crossing competitions, Birdman Competitions (Aarokokra and flying abilities are banned), fishing competitions. Maybe have a challenge where people have to try and reach into a barrel full of eels which can paralyse you for 10 minutes (con saves to resist the first, but disadvantage on subsequent animal handling) to get the prize at the bottom (animal handling checks), with a bench of rigid contestants slowly regaining their movement, with their outstretched arms strung with lights for the amusement of passers by? Maybe there are large, friendly creatures like manatees which you can run over as a challenge (falling in is ok because they are definitely not hippos, honest). A food stall with a magical staff of water repelling which makes a wall around them in the ocean just off the beach, where they serve hot food to ocean dwellers? Spear fishing competition (number of fish on a spear after 1 minute).