Open caissons are sunk into the ground by their own weight. A cutting edge of the caisson having a tapered inner face on loading-that is, raising of the steining-results in bearing failure by displacing the soil which is in contact with the cutting edge. The bearing capacity of the cutting edge and the soil flow mechanism depend on the configuration of the cutting edge, sinking depth and soil type. This paper presents the results of a series of 1g model tests, which investigate the effect of varying tapered angles of the cutting edge on the penetration resistance of the open caisson. The vertical failure load and corresponding vertical bearing capacity factor, N′γ, and the soil flow mechanism around the cutting edge are investigated. The soil flow mechanism and the influence of surcharge formed at the top level of the cutting edge due to advancement of the caisson in the ground are examined using the image-based deformation measurement technique. The results highlight that the cutting angle of the cutting edge and sinking depth play important roles in the load-penetration response and soil flow mechanism. © 2019 ICE Publishing: All rights reserved.