Observation of $\psi \left(3686\right)\to 3\varphi $

Using $\left(2.712±0.014\right)×{10}^{9}\text{}\text{}\psi \left(3686\right)$ events collected by the BESIII detector operating at the BEPCII collider, we report the first observation of $\psi \left(3686\right)\to 3\varphi $ decay with a significance larger than $10\sigma $. The branching fraction of this decay is determined to be $\left(1.46±0.05±0.17\right)×{10}^{-5}$, where the first uncertainty is statistical and the second is systematic. No significant structure is observed in the $\varphi \varphi $ invariant mass spectra.