The loop O(n) model is a family of probability measures on collections of nonintersecting loops on the hexagonal lattice, parameterized by (n, x), where n is a loop weight and x is an edge weight. Nienhuis predicts that, for 0 ≤ n ≤ 2, the model exhibits two regimes: one with short loops when x < x c (n), and another with macroscopic loops when x ≥ x c (n), where x c (n) = 1 2 + √ 2 − n. In this paper, we prove three results regarding the existence of long loops in the loop O(n) model. Specifically, we show that, for some δ > 0 and anywe can conclude the loops are macroscopic. Next, we prove the existence of loops whose diameter is comparable to that of a finite domain whenever n = 1, x ∈ (1, √ 3]; this regime is equivalent to part of the antiferromagnetic regime of the Ising model on the triangular lattice. Finally, we show the existence of non-contractible loops on a torus when n ∈ [1, 2], x = 1.The main ingredients of the proof are: (i) the 'XOR trick': if ω is a collection of short loops and Γ is a long loop, then the symmetric difference of ω and Γ necessarily includes a long loop as well; (ii) a reduction of the problem of finding long loops to proving that a percolation process on an auxiliary graph, built using the Chayes-Machta and Edwards-Sokal geometric expansions, has no infinite connected components; and (iii) a recent result on the percolation threshold of Benjamini-Schramm limits of planar graphs.