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Low-mass (<1.2 Msun) main-sequence stars lose angular momentum over time, leading to a decrease in their magnetic activity. The details of this rotation–activity relation remain poorly understood, however. Using observations of members of the ≈700 Myr old Praesepe and Hyades open clusters, we aim to characterize the rotation–activity relation for different tracers of activity at this age. To complement published data, we obtained new optical spectra for 250 Praesepe stars, new X-ray detections for 10, and new rotation periods for 28. These numbers for Hyads are 131, 23, and 137, respectively. The latter increases the number of Hyads with periods by 50%. We used these data to measure the fractional Hα and X-ray luminosities, LHα/Lbol and LX/Lbol, and to calculate Rossby numbers Ro. We found that at ≈700 Myr almost all M dwarfs exhibit Hα emission, with binaries having the same overall color–Hα equivalent width distribution as single stars. In the Ro–LHα/Lbol plane, unsaturated single stars follow a power law with index β = −5.9 ± 0.8 for Ro > 0.3. In the Ro–LX/Lbol plane, we see evidence for supersaturation for single stars with R < 0.01, following a power law with index βsup = 0.5(+0.2,-0.1) supporting the hypothesis that the coronae of these stars are being centrifugally stripped. We found that the critical Ro value at which activity saturates is smaller for LX/Lbol than for LHα/Lbol. Finally, we observed an almost 1:1 relation between LHα/Lbol and LX/Lbol, suggesting that both the corona and the chromosphere experience similar magnetic heating.