In the last few decades, a terribly pernicious rumor has been circulated by the press. It claims, exhibiting a level of stupidity heretofore considered impossible, that a human being could crawl through the arteries of a blue whale. Of course, nothing could be farther from the truth. I do not know why this deleterious rumor has been systematically repeated, but its very existence is an ugly cancer upon the face of science.
Yeah! How are you supposed to breathe while swimming in the blood? The blood pressure would kill you. The heart would pump you to the extremes where you'd get stuck in a narrow artery and probobly die and hurt the whale. And to get in there in the first place you'd probable let in a lot of ocean water as you cut the hole