The Hyrule Forest Park is a location in The Legend of Zelda: Breath of the Wild. It is located near near the Hyrule Castle Moat on the large island called East Hyrule Castle in the Hyrule Field region in the province of Central Hyrule. The Helmhead and Boneyard bridges allow access to the park. Link can find two hidden Koroks and a Treasure Chest containing a Phrenic Bow here. However a Guardian Stalker patrols the park's ruins while another patrols the forest near Helmhead Bridge. A Stalnox lives in the forest east of the park and the island's name is listed above its health bar as only Hyrule Forest Park is listed on the Sheikah Slate map (after the map data for the area has been acquired) once Link visits the location.
One of the four ancient pillars around Hyrule Castle was buried here though later rose up along with the others damaging the area northwest of the park.
Before the Calamity
The park was apparently a national forest park of Hyrule presumably visited by residents of Castle Town and Royal Family of Hyrule when they wanted to enjoy Hyrule's natural splendor close to home or to get away from the hussle and bussle of Castle Town. Presumably the park may have allowed Deer Hunting to control the island's Deer population which continue to thrive on the island a century after the Great Calamity despite the presence of Guardians and Stalnox. Presumably the people of Castle Town and Royal Family of Hyrule acquired Raw Prime Meat from hunting deer hear as Hyrule Castle West was essentially a prison island due to Castle Town Prison being located there and the Moat Bridge being the only land route thus hunting in Hyrule Castle West's forests was likely relegated to Hyrulean Soldiers and Knights of Hyrule that served as prison staff while Hyrule Forest Park was open to the general population. Hunting near the prison might be considered to dangerous for royalty unless proper precautions were taken with Hyrule Forest Park being a much safer alternative. It is implied Rhoam Bosphoramus Hyrule may have hunted here before the Great Calamity as his spirit is shown to have knowledge of hunting which is often a sport practiced by real world royalty and nobility. It was also not uncommon for royalty to own lands which only they or those they permitted were allowed to hunt and killing animals within said lands without proper permission counted as a form of theft. Thus its possible the Royal Family controled the hunting rights to the forest park which may have been exclusive to them and those they permitted to hunt with it being open for hunting to the public occasionally presumably during times of overpopulation though presumably it would be carefully regulated to maintain the island's ecosystem and prevent over hunting which would make sense as the Royal Family was apparently involved in attempts to prevent Silent Princess from going extinct by growing them domestically though Princess Zelda hoped they would thrive in the wild when all their efforts failed showing the Royal Family and Hylian people care above protecting the environment.
Great Deku Tree & Koroks
Additionally the park may have been set up near the castle and Castle Town out of respect for the Great Deku Tree and Koroks that live in nearby Great Hyrule Forest whom have a strong connection to Hyrule's forests and nature. The Royal Family apparently had formed strong relations with them given Princess Zelda was able to navigate the Lost Woods surrounding Korok Forest without difficulty as she was able to enter and leave it during the Great Calamity. Korok also are known to craft wooden weapons, bows, and shields for Hylians thus the Hyrule Forest Park may have been a sign of good will and respect between the Hylians and Koroks. Despite the dangers, Koroks can still be found hiding on the island a century after the Great Calamity possibly watching over the island's wildlife and surviving trees awaiting the day when Link defeats Ganon so the park can be restored to its former glory.