Got your comment Ash, so here I am. lol
Ok well first, before you consider any internship, make sure you can secure a job first, and that the job you choose is going to not only provide for your living expenses, but will also allot for extra "intern commute" money.
Obviously since you are already dreading this new job and haven't even started, it's a disaster waiting to happen, and in your situation, you can't afford to go with it now, set everything else up, and then have a mental blow-out and leave the job mid-semester. That would cause havoc.
Focus on finding a reliable, low-stress, familiar job with the skills you have right now. Once you lock that down, then head for the internships.
I personally voted to do both, because well, I'm crazy and have been there.
HOWEVER - If you want my honest and experienced opinion, you should do the Zoo internship, and save the Seaworld one for later. Why?
Simple really... While yes you love the aquatic side of nature (as do I), when entering this field, unless your credentials are superior to the vast majority (which they aren't at this point), you do not want to lock yourself into specific husbandry. What I mean by that, is that while working with Orcas is AMAZING (remember my pic!!), an internship specifically geared for those animals alone is going to limit your field experience, animal exposure and overall zoological knowledge.
Working at a Zoo however is going to expose you to a broad diversity of animals, husbandry tasks, operational duties, and species knowledge.
THAT is what is going to be the building block of your resume!!!
Here is why - Though Seaworld is a huge name, you would have to list your internship title and duties, and while they would all be important ones, they would all be centered around one main species - an animal of which many many places you might choose to work, do not house!
With the Zoo internship, you will be able to list every animal you have worked with, different equipment, enrichment tools, training techniques, exhibit maintenance, varied diet preps, mannerisms, observational studies, and so on and so forth. The list is huge because the number of animals is huge and so diverse, and each require different care, and provide you with the opportunity to absorb so much more knowledge and experience its crazy!
This means that later on, if you wanted to focus more on the aquatic angle, a future employer might say "Well, her aquatic experience is a bit limited - -BUT she has worked with so many animals that she has demonstrated great versatility and is quite experienced when it comes to general husbandry!"
Try that with a species specific internship and you are not only seriously limiting your choice of employers, but you also run the risk of hearing "Well, I am sure you have learned a great deal about Orcas, however our facility does not house them, or anything of their size, so what else would you have to offer?".... And that's when you would have a "Dam.mit moment".
Been there, done that. Do your best to avoid that.
Besides, I know Seaworld does internships Annually, so if you did the Zoo for a year and wanted to then branch out to Seaworld, then I would say go for it, because at that point it would be adding to your already established diversity, making you MORE marketable, instead of boxing you in! And that's what you want!!