Monster Energy Ultra Watermelon is low in calories. Watermelon: Caffeine from all sources: 150 mg per can. Monster Energy Ultra Paradise is low in calories. Paradise: Caffeine from all sources: 140 mg per can. Watermelon: Monster Energy Blend: Taurine, L-Carnitine, Caffeine, Inositol. Paradise: Monster Energy Blend: Taurine, L-Carnitine, Caffeine, Inositol.