In addition to WedsPashi's answers, in the past when I've waded and scrambled around coasts I've gotten scratched and pierced by sharp mussels and rocks. I had a friend once step on a particularly long barnacle which broke inside his foot and we had to go to the ER. Also bear in mind that sea caves are formed in places that ocean currents batter the coast, and with those currents come nasty debris like glass. So in general, going barefooted or barehanded is not advisable.
Also, while WedaPashi is right about being wary of king tides, sometimes caves and beaches are only accessible at king low tides. These sites tend to have the most wildlife, too, because of their remoteness. Just make sure to be very vigilant to do all your exploring within +- 30 minutes of lowest tide so you don't get stranded.
Make sure you have a plan in case you do get stranded. For instance, one cave I explored like this had a strong current running parallel to the coast. If I ever got stranded, the plan was to stay afloat and ride the current to a beach down the way.