thanks beachbunposts for the submission!
Hi there and congrats for trying.
About erections, yes don´t think too much about it.
It´s natural at the beginning being a bit self conscious about it but with time that will disappear for sure.
How to respond? Act calm and naturally, go to the water, lay down and relax whatever suits you best.
Does anyone care? As long as you don´t stroll the beach proudly flashing it to every women you encounter, no, otherwise it may be seen as offensive.