Captain Brineybeard looks like a stereotypical cartoon pirate, with an eye patch and two wooden peg legs. He wears a slightly torn grey shirt with the sleeves seemingly stitched on. He also wears a belt with a golden, rectangular buckle, with deep red pants. Captain Brineybeard has a deep red nose, a short, but shaggy black beard, and a red head scarf with a yellow or golden line across it. He dons a golden ear piercing.
Captain Brineybeard seems to taunt his opponents before fighting them, this is hinted at the base part of the level as he laughs at both Cuphead and Mugman before they even begin to battle him. His language appears to be that of a stereotypical pirate.
He seems to have joy in having brawls with others, for he never really frowns during the entire battle against him, except when he is thrown off of his own ship, and when beaten in simple mode. Either that, or he is overconfident even when his soul is threatened to be taken by a cup and a mug.
However, the personality of his ship seems to enjoy deriding its rivals, evident by the 2nd phase death screen.
Captain Brineybeard laughs smugly at Cuphead and Mugman before the battle commences.
Phase 1 & 2
"Yer skills be like me buried treasure...just a myth!"
—Captain Brineybeard, Phase 1 & 2 death screen
Throughout the battle, an angry-looking barrel moves back and forth across the screen and will crush the players if they are underneath it. After slamming onto the dock, the barrel will have an innocent expression for a few seconds upon being hoisted up and returning to its usual state. In Simple mode, the barrel moves slower and it will take longer to attack again. In Expert mode, it moves faster and it will take less time to attack again.
After taking enough damage, Brineybeard will summon one of three aquatic creatures by whistling to aid him in battle:
- A shark arrives from the left side of the screen, which can be seen in the background accompanied by two sirens. This shark will attempt to bite the players unexpectedly from the left side, covering the fifth plank after the first pole, and then scurry back to the ocean. Shooting the shark at least once will increase its retreating speed by 30%. In Simple Mode, the shark will only cover the third plank after the first pole and shooting it will increase its retreating speed by 42%. In Expert mode, the shark will be covering up to the second pole (or the seventh plank after the first pole) and shooting it will increase its retreating speed by 18%.
- A squid unexpectedly shows up and flings ink blobs around sporadically. The player can shoot it to stop it from attacking. While the ink blobs and the squid itself do not damage the players, the ink blobs will darken the screen if the players are hit by the ink blobs, it will darken the screen three times and additional ink blobs will increase the duration of the effect. Hitpoints = 41-61/31-61/45-71
- A group of 4 dogfishes appear from the right side of the screen that can be noticed by the periscope that appears after the whistle. The dogfishes will attempt to bite the player by jumping from the water to the dock and scurrying towards them. They can be easily disposed of by shooting them. In Simple mode, only 2 dogfishes will come out simultaneously before the periscope sinks. In Expert mode, the dogfishes will come out before the periscope sinks and at a faster rate. Hitpoints = 3/3/3
Nearly halfway through the phase, the ship will begin to fire a single cannonball at the players throughout the rest of the phase, which can be noticed by the ship chewing. In Simple mode, the ship is able to shoot when the battle begins, but with a random interval and the cannonball travels slower. In Expert mode, the cannonball travels faster with a higher rate of shooting, and the ship will start shooting earlier than regular mode.
After taking enough damage, Brineybeard's ship charges up with a sick expression before turning into a narwhal-like creature, knocking Brineybeard off the ship in the process and commencing the final phase of the battle with a loud roar. In Simple mode, the ship will sweat and pant heavily rather than turning into a narwhal-like creature, and Brineybeard will remain on it but vigorously rubbing his eyes as the battle ends. Hitpoints = 1000/936/952
—Captain Brineybeard's ship, Final phase death screen
In the final phase, players battle Brineybeard's ship with its exposed uvula as its weak point. The uvula has two known attacks:
- Its first attack involves shooting three looping fireballs that can be avoided by ducking. In Expert mode, the fireballs travel faster, but only two will be shot.
- The ship will close its mouth and charge up before firing a giant pink laser that goes across the screen. Players can avoid the attack by parrying continuously or simply ducking underneath it.
The barrel from the previous phase still remains and repeats what it does in the previous phase: crushing the players if they are underneath it.
After taking enough hits, the ship is defeated as it groans in pain while tilting side-to-side with its uvula. Hitpoints = 264/448
|Captain Brineybeard's introduction.|
|The barrel dropping itself down.|
|Captain Brineybeard whistling for help.|
|The shark signals its arrival.|
|The dogfish signal their arrival.|
|The squid arrives.|
|The boat chewing and spitting out a cannonball.|
|The boat transforms.|
|Captain Brineybeard screaming when defeated on Simple mode.|
|The boat fires a beam.|
|Regular Mode||Expert Mode|
- Originally, Captain Brineybeard was named Captain Silver in one of the 2013 trailers. The name Captain Silver is a reference to the infamous pirate captain, Long John Silver.
- Also, in early sketches shown in an interview, Captain Brineybeard was also going to be called "Paul the Pirate".
- A slowed down version of his track is heard in the good ending credits.
- In the 2015 Demo, Brineybeard's battle theme was the prototype version of Wally Warbles' theme, Aviary Action!.
- For one frame during the second phase transition, the ship overlaps Captain Brineybeard.
- Brineybeard's battle theme, Shootin N' Lootin, was the placeholder theme for Cagney Carnation's stage Floral Fury, as seen from footage from the 2016 Cuphead demo.
- The theme that plays during the fight is one of the few boss themes that isn't used in Admission to Perdition or One Hell of a Time. The others being Murine Corps, Honeycomb Herald, and The Kings Court.
- Brineybeard bears a strong visual similarity to the main antagonist of Popeye Bluto in his depiction as Sindbad the Sailor in the 1936 cartoon Popeye the Sailor Meets Sindbad the Sailor and the pirates from the Silly Symphony short, King Neptune.
- The first part of his name, "Briney," is derived from the word "brine" which means either as "water of an ocean or a sea" or as "large body of salt water".
- Captain Brineybeard and Cala Maria are the only nautical bosses in the entire game.
- Captain Brineybeard's ship's Death Screen is the first game over screen that's just a sound, the second being Werner Werman's robot cat.
- The squid is an obvious reference to the Blooper from the Mario franchise, which darkens the screen with its ink so that the player can't see what's going on.
- The shark makes a resemblance with the shark in Silly Symphony short, Peculiar Penguins.
- The first phase of this battle has some similarities to the first boss battle with the Steam Powered Oceanic Tinker Tub in Shantae: Risky's Revenge such as both ships being sentient.
- Brineybeard's ship bears a huge resemblance to a fish in the 1939 Fleischer cartoon Small Fry.
- He is one of the two human bosses in the game. (As in humans that do not transform.) The other is Sally Stageplay.
- Although Dr. Kahl is also a human, he does not count because he is technically not the main boss, but his robot is.
- He is the only character to have five fingers on each hand.
- Captain Brineybeard, along with Ribby and Croaks and Cala Maria, is one of the few bosses to have a custom knockout animation in Simple mode.
- Brineybeard's name is a parody of the pirate known as Edward Teach, AKA, Blackbeard. It also doubles as a reference to the British Historical Parody film Yellowbeard, which features a similarly named pirate.
- This boss' barrel might be a reference to Metal Slug 4 Level 8 boss' laser claw, as it can also dive down if the player stands under it.
- Brineybeard possibly has the most attacks than any other boss, including the barrel and ship and his calling for the shark, the squid, and the dogfish.