A balloon can be designed with excessive slack for accommodating the dramatic pressure differential between ground level and typical weather balloon altitudes,

A balloon can be designed with excessive slack for accommodating the dramatic pressure differential between ground level and typical weather balloon altitudes, but neither airships (rigid or semi-rigid) nor blimps could ever hope to come close. Airships would fail to enclose enough volume power structural weight and blimps tailored for high altitude would fail to keep shape at lower altitudes. Even if the problem was somehow solved for blimps, (perhaps with an internal "diving bladder" filled by compressing some of the carrying gas), their cross section at lower altitudes would be prohibitively big, making them effectively unmaneuverable. A very high altitude blimp would effectively be a one-way vehicle, it could raise as an uncontrolled balloon (then it might even be acceptable to not solve the slack issue at all), then operate as a dirigible at target altitude.