A Blue Whale's heart is so large that you could swim through its arteries.
The blue whale is a massive creature and is the largest living animal in the world; even larger than most dinosaurs. The largest of the blue whales can measure in at over 100 ft in length and can weigh in excess of 180 tons at its largest.
In fact, everything about the blue whale is large including its, arteries and heart. On average most blue whales grow to be around 70 – 90 ft in length, weigh around 100 – 150 tons. In order to get blood through the blue whale's large body, it has massive arteries, which pump blood through the heart and into its major vital organs.
The arteries are so large in fact that a full-size human could swim through them.