In a book that I'm reading there is a sentence like this

If we focus just on our local galaxy, we know that there are about 100 billion stars, with about 20 billion Earth-like planets. Twenty billion makes for a lot of petri dishes for creating life.

So the numbers seem encouraging, but now we get into more difficult waters: How many livable planets actually have life?

My question is what does get into more difficult waters mean?

Please explain to me.


  • 1
    google 'difficult waters'
    – lbf
    Commented Mar 20, 2018 at 15:06

2 Answers 2


This usage is a simple analogy to challenging navigation in a waterborne vehicle. Difficult waters simply refers to something hard or demanding.

To "get into more difficult waters" means to start to tackle more difficult problems. In this particular context, they are saying that it's harder to determine an accurate value for N in the Drake equation seeing as it's very difficult to accurately estimate fl, the fraction of planets that can potentially support life that actually develop life.

Note, I wouldn't really consider this to be idiomatic in the same way as the similar troubled waters which means a situation that is fraught with difficulty, danger, confusion, stress, etc.


You can make an analogy to sailing the ocean. When the ocean gets rough it becomes harder to get to your destination. He's saying it is hard to answer how many planets have life.

  • I know the author means it's hard, but I just want to know that is get into more difficult water an idiom, and has other meaning. That's why I decided to ask here. Commented Mar 20, 2018 at 14:40
  • 2
    @Knumber10 In that case, please edit your question to clarify. We are not clairvoyant.
    – choster
    Commented Mar 20, 2018 at 14:44

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