Hey,
There is a lot more that you can do after your Bachelors in Science other than the Masters(A good option though,if you are inclined towards making a career in academics or research sector).
Well,a B.Sc degree equips you with deeper understanding of science and inculcate the spirit of reasoning that make you ponder before coming to any conclusion.
If you don't want to go for Masters in Science you can switch to all new streams for instance  Journalism,Animation,Computer Technology,Management,Hospitality Sector,MBA,Law,MCA. You may even go for several fields like Space Research Institutes,Agriculture Industries,Oil Industry,Research Firms,Forensic Crime  Research,Wildlife and Fishery Department,Chemical Industries and so on. You may even go for  civil services,Banking or Finance sector and the list is endless.It all depends on your calling.
Hope this helps.
Good luck.