ocean.tex

\begin{tikzpicture}

\draw[<->] (0,6) node[left] {y} -- (0,0) -- (6,0) node[below] {x};

\draw[thick, double, double=green, blue, fill=blue!30!white] (0,0)rectangle(5,5);
\draw (5,2.5) node[right] {boundary};
\draw[dotted] (0,0) -- (0,-1);
\draw[<->] (0,-1) -- (5,-1);
\draw[dotted] (5,0) -- (5,-1);
\draw (2.5,-1) node[below] {\emph{size}};

\draw[rotate=-45, xshift=-0.5cm, <->] (-1,0) -- (-1,7.1);
\draw[rotate=-45, dotted] (-1,0) -- (-1.5,0);
\draw[rotate=-45, dotted] (-1,7.1) -- (-1.5,7.1);
\draw (1,4) node {\emph{length}};

\draw[rotate=-45, yshift=-1cm, <->] (-1,0) -- (1,0);
\draw[rotate=-45, dotted] (-1,0) -- (-1,-1);
\draw[rotate=-45, dotted] (1,0) -- (1,-1);
\draw (-1,-1) node {\emph{width}};

\draw[rotate=-45, thick, double, double=yellow, color=green!30!white!80!blue, pattern color=green ,pattern=north east lines] (-1,0)rectangle(1,7.1) node[black, right] {\emph{current}};

\draw[->, red, thick, xshift=0.7cm, yshift=-0.7cm] (2,2) node[right, black] {\emph{strength}} -- (2.5,2.5);

\draw[thick, color=red, fill=pink] (0,0) node[anchor=north east, black] {\emph{start}} circle (0.1);
\draw[thick, color=red, fill=pink] (5,5) node[anchor=south west, black] {\emph{end}} circle (0.1);


\foreach \x/\angle in {-0.5/90, 0/90, 0.5/90} {
    \foreach \y in {0.5, 1.5, 2.5, 3.5, 4.5, 5.5} {
        \draw[->,thick, rotate=-45, green!50!black]  (\x, \y) -- ++(\angle:0.7);
    }
}

\end{tikzpicture}