The Quicksand Ring is a Magical Ring that Link acquires in Oracle of Seasons and Oracle of Ages. In both Oracle of Seasons and Oracle of Ages, Link can acquire the ring by planting a Gasha Seed and finding it within a Gasha Nut. Link can also acquire it in a Seed Ring form by bumping into Maple.
"No sinking in quicksand"
In Oracle of Seasons, Link can acquire the Quicksand Ring inside a Cave located in North Horon. The cave is one screen north and one screen east of the Gnarled Root Dungeon and can only be accessed using Flippers. In order to reach this cave, Link first needs to change the season to Autumn. The corresponding Tree Stump is found on the west side of the river, directly four screens west of Gnarled Root Dungeon. There is no direct path from Gnarled Root Dungeon, so Link has to maneuver from screen to screen. More precisely, the Tree Stump is found one screen north of Mrs. Ruul's Villa.
Once Link reaches the Tree Stump, change the season to Autumn. Make the way to the area that is one screen north of Gnarled Root Dungeon. Lift up the Mushrooms with the Power Bracelet and head east. Enter the Cave to find a Treasure Chest that contains the Seed Ring.
When equipped, Link is able to walk on Quicksand without sinking. The Quicksand Ring also prevents Link from sinking into Whirlpools, such as the ones that surround the Sea of Storms in Oracle of Ages.