First permafrost carbon models suggest that deep carbon pools need to be considered for simulating the full permafrost-carbon feedback. After Hugelius et al. (2014) we consider "deep" soil carbon pools as those found below 3 meter from the land surface. Though all permafrost can be affected by degradation, thawing and erosion of thick permafrost deposits containing ice and carbon may cause particularly strong feedbacks to permafrost ecosystems by surface subsidence and to the carbon cycle by releasing substantial amounts of carbon previously frozen for millennia. In this synthesis study we aim at discussing the size, distribution, qualities and vulnerabilities of deep carbon pools in peatlands, Yedoma, river deltas, thermokarst basins, and other deep deposits in permafrost regions to evaluate opportunities for a comprehensive synthesis of existing datasets.