Tropical tropopause layer (TTL) clouds have a significant impact on the Earth’s radiative budget and regulate the amount of water vapor entering the stratosphere. Estimating the total coverage of tropical cir- rus clouds is challenging, since the range of their optical depth spans several orders of magnitude, from thick opaque cirrus detrained from convection to sub-visible clouds just below the stratosphere. During the Strateole-2 observation campaign, three microlidars were flown on board stratospheric superpressure balloons from October 2021 to late January 2022, slowly drifting only a few kilometers above the TTL. These measurements have un- precedented sensitivity to thin cirrus and provide a fine-scale description of cloudy structures both in time and in space. Case studies of collocated observations with the spaceborne Cloud-Aerosol Lidar with Orthogonal Polar- ization (CALIOP) show very good agreement between the instruments and highlight the Balloon-borne Cirrus and convective overshOOt Lidar’s (BeCOOL) higher detection sensitivity. Indeed, the microlidar is able to de- tect optically very thin clouds (optical depth τ < 2 × 10−3) that are undetected by CALIOP. Statistics on cloud occurrence show that TTL cirrus appear in about 50 % of the microlidar profiles and have a mean geometrical depth of 1 km. Ultrathin TTL cirrus (τ < 2 × 10−3) have a significant coverage (23 % of the profiles), and their mean geometrical depth is 0.5 km.