def plot_drawdown_underwater(returns, ax=None, **kwargs):
if ax is None:<EOL><INDENT>ax = plt.gca()<EOL><DEDENT>y_axis_formatter = FuncFormatter(utils.percentage)<EOL>ax.yaxis.set_major_formatter(FuncFormatter(y_axis_formatter))<EOL>df_cum_rets = ep.cum_returns(returns, starting_value=<NUM_LIT:1.0>)<EOL>running_max = np.maximum.accumulate(df_cum_rets)<EOL>underwater = -<NUM_LIT:100> * ((running_max - df_cum_rets) / running_max)<EOL>(underwater).plot(ax=ax, kind='<STR_LIT>', color='<STR_LIT>', alpha=<NUM_LIT>, **kwargs)<EOL>ax.set_ylabel('<STR_LIT>')<EOL>ax.set_title('<STR_LIT>')<EOL>ax.set_xlabel('<STR_LIT>')<EOL>return ax<EOL>
Plots how far underwaterr returns are over time, or plots current
drawdown vs. date.

Parameters
----------
returns : pd.Series
    Daily returns of the strategy, noncumulative.
     - See full explanation in tears.create_full_tear_sheet.
ax : matplotlib.Axes, optional
    Axes upon which to plot.
**kwargs, optional
    Passed to plotting function.

Returns
-------
ax : matplotlib.Axes
    The axes that were plotted on.