Wicked temper

My son's just shy of 18 months and he's started having some wicked tantrums. Today was a bad one...he went down for a nap and it was short which is unusual. He usually goes for about 2 and a half to 3 hrs and this time it was about 1 hour and 15. Well he woke up fine, everything seemed good. He's playing,etc and all of a sudden he just starts whining and turns full blown tantrum over a toy. I tried ignoring him, I tried taking the toy and directing him elsewhere, and I also tried holding him and singing. Singing helped the best but he had his cup and was drinking and it became empty and he lost his damn mind all over again..The length of time these are stretching are concerning..what do I do about these tantrums??