  Decay rates and time-dependent and direct CP asymmetries in the decays
$B^0\to K^+K^-K_{S(L)}$ and $K_S K_S K_{S(L)}$ are studied. Resonant and
nonresonant contributions to the three-body decays are carefully investigated.
Nonresonant effects on 2-body and 3-body matrix elements are constrained by QCD
counting rules. The predicted branching ratios are consistent with the data
within the theoretical and experimental errors, though the theoretical central
values are somewhat smaller than the experimental ones. Owing to the presence
of color-allowed tree amplitudes in $B^0\to K^+K^-K_{S(L)}$, this
penguin-dominated mode is subject to a significant tree pollution and the
deviation of the mixing-induced \CP asymmetry from that measured in $B\to
J/\psi K_S$, namely, $\Delta \sin 2\beta_{K^+K^-K_{S(L)}}\equiv \sin
2\beta_{K^+K^-K_{S(L)}}-\sin 2 \beta_{J/\psi K_S}$, can be as large as O(0.10).
In contrast, the $K_SK_SK_{S(L)}$ modes appear theoretically very clean in our
picture with negligible $\Delta\sin 2\beta_{K_SK_SK_{S(L)}}$. Direct CP
asymmetries in $K^+K^-K_{S(L)}$ and $K_S K_S K_{S(L)}$ modes are found to be
very small.
