  The initial data sets for the five-dimensional Einstein equation have been
examined. The system is designed such that the black hole ($\simeq S^3$) or the
black ring ($\simeq S^2\times S^1$) can be found. We have found that the
typical length of the horizon can become arbitrarily large but the area of
characteristic closed two-dimensional submanifold of the horizon is bounded
above by the typical mass scale. We conjecture that the isoperimetric
inequality for black holes in $n$-dimensional space is given by $V_{n-2}
\lesssim GM$, where $V_{n-2}$ denotes the volume of typical closed
$(n-2)$-section of the horizon and $M$ is typical mass scale, rather than
$C\lesssim (GM)^{1/(n-2)}$ in terms of the hoop length $C$, which holds only
when $n=3$.
