Subterranean termites live underground and build tunnel networks to obtain food and nesting space. Afterobtaining food, termites return to their nests to transfer it. The efficiency of termite ment throughthe tunnels is directly connected to their survival. Tunnels should therefore be optimized to ensure highlyefficient returns. An optimization factor that strongly affects ment efficiency is tunnel curvature.In the present study, we investigated traveling behavior in tunnels with different curvatures. We thencharacterized traveling behavior at the level of the individual using hidden Markov models (HMMs)constructed from the experimental data. To observe traveling behavior, we designed 5-cm long artificialtunnels that had different curvatures. The tunnels had widths (W) of 2, 3, or 4 mm, and the linear distancesbetween the two ends of the tunnels were (D) 20, 30, 40, or 50 mm. High values of D indicate low curvature.We systematically observed the traveling behavior of Coptotermes formosanus shiraki and Reticulitermessperatus kyushuensis and measured the time () required for a termite to pass through the tunnel. UsingHMM models, we calculated  for different tunnels and compared the results with the  of real termites.We characterized the traveling behavior in terms of transition probability matrices (TPM) and emissionprobability matrices (EPM) of HMMs. We briefly discussed the construction of a sinusoidal-like tunnelsin relation to the energy required for termites to pass through tunnels and provided suggestions for thedevelopment of more sophisticated HMMs to better understand termite foraging behavior.