We have measured the high-magnetic-field dependences (up to 18 T) of the in-plane and out-of-plane transport properties of ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8}$ (Bi-2:2:1:2) single crystals. From I-V curves of c-axis transport we extract the magnetic field and temperature dependences of the interlayer critical current and define a decoupling line ${\mathit{H}}_{\mathit{D}}$(T) above which ${\mathit{J}}_{\mathit{c},}$c vanishes. The temperature dependence of ${\mathit{J}}_{\mathit{c},}$c supports a first-order decoupling transition. The decoupling line lies close to the irreversibility line in the field interval 0.5--5 T. The field dependence of the in-plane vortex activation energy is \ensuremath{\sim}${\mathit{B}}^{\mathrm{\ensuremath{-}}0.5\ifmmode\pm\else\textpm\fi{}0.1}$.