Nov 2, 2016
Hello all, I have a question about NROTC. I will be applying to an NROTC program soon. My question is, if I choose Marine option, do I still have the option to switch to Navy later on? My Marine Corps recruiter claims that the option doesn't really matter because you choose before your sophomore year. Is this true? All answers are appreciated.
After I am in the NROTC program can I switch between Navy, Navy Nurse, and Marine Corps options?

There are some limited opportunities to switch between options but being allowed to switch between options is not guaranteed. Students that wish to switch options will be evaluated based on their achievements in the program, physical fitness test scores, and academic grades.

You can apply to one, Navy or Marine Option. You can apply to switch, but it is all up to the needs of the service. So it's a numbers game, how is your performance, your reasons, etc. whichever one you initially select, be prepared to stay in that one.
Thanks @AROTC-dad and @NavyHoops . Would you think that switching from Marine to Navy option is easier? The reason I ask is I'm really involved with the Marine Corps poolees and I enjoy working with them. But recently I've been thinking about my career and the Navy has some options I really like. I just wish I didn't have to lock in my path so early.
Marine is not focused on your choice of major. NROTC is very STEM focused, so I think switching to MO may be easier but I would speak to a Marine OSO (not an enlisted recruiter) about this.

Also I defer to @NavyHoops, who is an actual Marine officer.
Generally, people who switch once in the program switch from Navy to Marine Option. Switching the other way requires you meet certain academic requirements regarding calculus and physics. Also, depending on how long you wait, you might need to catch up on the Navy Option NROTC curriculum which is more extensive than Marine Option (all those sea navigation courses, etc.)

As others have pointed out you would need to apply to switch either way and it's a national board (read competition) that makes the assessment on whether you can switch. It is not something decided by your local officer team or even battalion.
To throw this out there, change of options, whether Navy to Marine or Marine to Navy, are difficult and rare. You can apply (starting after freshman year), but expect to get turned down. The Green to Blue board happens every summer, and for summer 2016:

-There were 7 Marine to Navy change of option nominations for rising sophomores- 1 was selected
-There were 3 Marine to Navy change of option nominations for rising juniors- 0 were selected*
*Of note- all three were offered the option of dropping their Marine scholarship and accepting Navy option Advance Standing

I don't have the Blue to Green numbers handy. Bottom line, don't walk into an NROTC unit thinking that you can just flip back and forth at will, because it does NOT work like that.
@USNA Applicant I am currently a Marine Option NROTC Midshipman and I have actually faced this dilemma myself. You can in fact switch Marine to Navy (or vice versa) after receiving the Marine/Navy Scholarship but there are some stipulations. First, you have to reapply for the respective service's scholarship. Also, you will have to change your 4 year course plan due to the added requirements that the Navy options have to satisfy. Based off of these stipulations it is easier to go from Marine option to Navy option (in the sense of the scholarship) but harder to go from Marine to Navy due to academic requirements.