The bending arts of Avatar: The Last Airbender came in a wide variety of shapes and sizes, and even if there were only four elements benders could manipulate with their martial prowess, there seem to be an infinite variety of ways to apply them. As the bending art with the most substyles and variety, Waterbenders show off an impossible assortment of moves throughout the shows, comics and Kyoshi novels. But just which feat in the entire series is the most powerful?
When ranking the power of bending acts in Avatar, the first step always comes in separating those performed by Avatars from those performed by non-Avatars. The master of all four elements reincarnated into every generation doesn't just enjoy the variety that comes with bending all the elements, but a natural boost in power that makes them one of the most powerful benders of each respective element in their generation. This means that there are actually three big categories when selecting the best showings of bending prowess: Avatars with the Avatar State, Avatars without it and non-Avatars.
In each category, selecting the move isn't just about raw power, but also the amount of precision and creativity of the skill displayed. Among showings with the Avatar State there are plenty of big contenders: Kuruk creating a massive tidal wave or Korra unleashing waves as large as Kuvira's mech before freezing it solid both come to mind. But frankly, this is a rare case where one of the greatest displays in the series came relatively early on, in the Season 1 finale.
Aang entering the Avatar State and merging with the ocean spirit La proved to be one of the most devastating displays of waterbending, completely without equal. Taking the shape of a giant koi fish made of water, Aang single-handedly repelled the Fire Nation invasion of Agna Qel'a by sweeping away fleets of ships and slashing them apart.
When it comes to selecting the greatest waterbending feat by an Avatar not in the Avatar State, things get a little tricky. Water is one of the most rarely-employed elements by the Avatars, who tend to prefer more readily-available elements for their attacks. But two showings stand out above the rest. The first comes from Roku, whose duel against his waterbending master commanded a colossal wave that tore through an iceberg and into the city in its path. In terms of the sheer amount of water and the force produced, it may be one of the most powerful.
However, it's Kyoshi who edges Roku out with a showing from her latest novel, The Shadow of Kyoshi. When intimidating a Fire Nation noble, Kyoshi uses waterbending to push a moored ship 100 yards out to sea before raising it open and freezing it in place. There's just no waterbending in the series save for those produced with the Avatar State that come anywhere close to that level of power with that degree of control.
But what about the non-Avatars? It's almost hard to think of big displays of power when it comes to Waterbenders throughout the franchise, with most preferring a finely controlled, sleek approach to fighting. Prominent examples that come to mind are Ming Hua, whose many-armed technique commanded precision seldom seen elsewhere, or Yakone, whose genetic ability to bloodbend without a full moon paralyzed an entire courthouse filled with the world's strongest benders.
The problem with granting either of those benders the top spot is that they excel solely in the uniqueness department, and given just how unique they are, there's little known about how much effort their techniques require or whether they'd really stack up against stronger moves. The same problem holds for Yakone's children, as neither Tarrlok nor Amon showcase anything particularly impressive with their waterbending outside bloodbending. Amon's column of water comes close, but by the timeline of the comics, Katara uses water to enhance her mobility so routinely that Amon's impressiveness lags far behind.
If you're looking for bare strength, the same duel in which Roku produced his own tidal wave saw his unnamed master perform an almost equally impressive waterbending move, commanding a huge serpent of water that drilled through the iceberg they fought upon. Though the move lacks precision or uniqueness, it's almost tempting to say that feat is the best in the series based on power alone.
Of course, it's impossible to talk about master Waterbenders without bringing up Pakku, and during "The Siege of the North" viewers got a chance to watch the old master unleash his power in battle against the Fire Nation. While many of his moves against Katara in their duel were impressive, it became clear from his fight during the invasion how much he was holding back. He fought atop a column of liquid that nimbly dodged around fire blasts before expanding it out into a powerful radial blast, and even sliced through entire tanks to disable them. Both are strong contenders.
To be the truly best it's not enough to exceed all the others in any one metric, but in all metrics at once. To that end, the truly best display of waterbending prowess comes from Katara, who ties herself for the top spot in the same episode. Season 3's debut saw Katara not only produce a tidal wave that swept away an entire battleship, but also saw her raise a gargantuan wall of steam from the ocean that obscured multiple ships. Both feats command more water than almost any other non-Avatar in the franchise, and steam-production is so rare Katara proves she's every bit as unique as Ming Hua or Yakone. In terms of power, control and novelty, it looks like Katara takes the gold.