"Really?" He's allowing himself to get a little too wrapped up in this because the idea that Sherlock Holmes would be pleased with him is almost enough to make Shinichi forget that that actually isn't possible.

"Thank you for the offer, but I think I'll be okay. I've been in a lot worse situations than on a mysterious cruise ship." He'll old off on listing them, a child in grave danger tends to be upsetting for a lot of people and since Watson is depicted as usually being compassionate he'll hazard a guess that he would not like to know about all the life threatening danger Conan tended to find himself in on what was nearly a daily basis.