We present new (2+1)-dimensional extended KdV (KdV2) equation derived within an ideal fluid model. Next, we show several families of analytic solutions to this equation. The solutions are expressed by functions of argument $$\xi = (k x +l y-\omega t)$$
ξ
=
(
k
x
+
l
y
-
ω
t
)
. We found the soliton solutions in the form $$A\,\text {sech}^{2}(\xi )$$
A
sech
2
(
ξ
)
, periodic solutions in the form $$A\,\text {cn}^{2}(\xi ,m)$$
A
cn
2
(
ξ
,
m
)
and superposition solutions in the form $$\frac{A}{2}[\text {dn}^{2}(\xi ,m)\pm \sqrt{m}\,\text {cn}(\xi ,m)\text {dn} (\xi ,m)]$$
A
2
[
dn
2
(
ξ
,
m
)
±
m
cn
(
ξ
,
m
)
dn
(
ξ
,
m
)
]
analogous to the solutions of (1+1)-dimensional, extended KdV equation and to the solutions to ordinary Korteweg-de Vries equation. On the other hand, the existence of these families of analytical solutions for the highly nonlinear non-local (2+1)-dimensional, extended KdV equation is astounding. The existence of essentially one-dimensional solutions to the (2+1)-dimensional extended KdV equation explains the enormous success of the one-dimensional nonlinear wave equations for the shallow water problem.