When Cersei Lannister laments that she has not seen her daughter Myrcella Baratheon in over a year, Oberyn Martell informs her that the last time he saw Myrcella she was swimming in the Water Gardens with two of his daughters, laughing in the sun.Doran Martell resides in the Water Gardens, largely confined to a wheelchair, and privately mourns the death of his brother Oberyn in a trial by combat against Gregor Clegane. Ellaria Sand arrives to demand vengeance for Oberyn; Areo Hotah, the captain of the guards, initially blocks her path but Doran bids him to let her pass. Doran continues to insist that he will not drag Dorne into a war, and forbids Ellaria's suggestion that they take personal revenge by harming Cersei's daughter Myrcella, who is currently in the Water Gardens. Doran says no harm is to come to Myrcella so long as he rules; Ellaria questions how much longer that will be, and storms out.
Jaime Lannister and Bronn (on a mission from Cersei) attempt to rescue Myrcella from the Water Gardens, but are stopped by the Sand Snakes (seeking revenge for Oberyn) sparking a fierce fight between the two parties. Ultimately a contingent of Doran Martell guards led by Areo Hotah capture both parties (as well as Ellaria Sand for sending out the Sand Snakes). Jaime is held prisoner in comfortable quarters where he meets Myrcella who insists she won't abandon her betrothal to Trystane Martell. Bronn meanwhile is kept in a conventional prison cell adjacent to the Sand Snakes' own cell, where it is revealed that Tyene Sand had poisoned the dagger she wounded Bronn with during their fight. As Bronn feels the effects of the poison, Tyene offers him an antidote if he declares her the most beautiful woman in the world, which he does. Tyene proceeds to give Bronn the antidote.
Ellaria begins her coup for Dorne in the Water Gardens, starting with Tyene killing Areo and Maester Caleotte, whilst Ellaria herself kills Doran. This is later extended from the Water Gardens, as Trystane is killed by Obara Sand.
In the books
In the A Song of Ice and Fire novels, the Water Gardens are located on a beach next to the Summer Sea, three leagues to the west of Sunspear on a coastal road (about nine miles). They were raised by Prince Maron Martell as a gift for his new bride, Princess Daenerys Targaryen to mark the union of Dorne to the rest of the Seven Kingdoms. Pale pink marble paves the gardens and courtyard. Terraces overlooking the numerous pools and fountains of the Water Gardens, shaded by blood orange trees, can be reached via a fluted pillar gallery leading to a triple archway.
The Water Gardens are pleasant in autumn: hot days, cool nights, the salt breeze blowing in from the sea, and fountains and pools to admire and play in. It is one of the few places, if not the only one, in the Seven Kingdoms where highborn and lowborn children can play as equals. One day when the sun was hot, Princess Daenerys took pity on the children of the servants and guards and allowed them to play in the pools with the highborn children, starting a tradition that is still kept in Dorne to this day.
In the books, Prince Doran Martell is known to have taken residency at the Water Gardens for some time, and is known to enjoy taking his mind off his troubles by watching the children playing in the pools.
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