I was in Diani last Xmas and the Likoni ferry was not that bad. Average Waiting time was 15 to 30 minutes....but that was 3 months ago.
I've heard of some by-pass routes but have never used them: (1) Miritin - Kinango - Kwale - Diani OR (2) Mazeras - Kinango - Kwale - Diani.
Perhaps you can try them out and let us know
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