  We consider the class of locally boost isotropic spacetimes in arbitrary
dimension. For any spacetime with boost isotropy, the corresponding curvature
tensor and all of its covariant derivatives must be simultaneously of alignment
type ${\bf D}$ relative to some common null frame. Such spacetimes are known as
type ${\bf D}^k$ spacetimes and are contained within the subclass of degenerate
Kundt spacetimes. Although, these spacetimes are $\mathcal{I}$-degenerate, it
is possible to distinguish any two type ${\bf D}^k$ spacetimes, as the
curvature tensor and its covariant derivatives can be characterized by the set
of scalar polynomial curvature invariants for any type ${\bf D}^k$ spacetime.
In this paper we find all type ${\bf D}^k$ spacetimes by identifying degenerate
Kundt metrics that are of type ${\bf D}^k$ and determining the precise
conditions on the metric functions.
