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. essential for building upgraded Strontium modules. located in deep biomes near the Alien Ruins. to harvest you need a Sonic Resonator to gather Celestine before returning to base. Tadpole upgrades progress depends on Celestine, and travelers should watch for dangerous patrols in the area. Air supply and combat readiness are crucial while mining.