Celestine in Subnautica 2 is described as a rare mineral found in the biome around the Alien Ruins at deep depths; typically around 200 meters southeast of the Ruins near Needler nests, where players use a Sonic Resonator to harvest it and then return to craft the Tadpole Depth module. Sources indicate Celestine is used to craft Strontium-related equipment and is tied to progressing Tadpole upgrades, with dangerous patrols near the resource. Players are advised to approach cautiously, ensuring Oxygen supply and defense against nearby enemies as they mine and extract Celestine. needed for crafting Strontium gear. located in deep biomes around Alien Ruins. to harvest you need a Sonic Resonator to gather Celestine prior to returning to base. Tadpole upgrades progress depends on Celestine, and travelers should expect dangerous patrols in the area. Air supply and defense against enemies are crucial while mining.