I have experimented a bit with Whirlpools, and have concluded the following:
Each Whirlpool is connected to one other Whirlpool. Which other Whirlpool you end up at when entering one is 100% consistent. However, Whirlpools are NOT bi-directional (theoretically, there could be a bi-directional pair, but I doubt one exists). Instead, each Whirlpool only has a certain 'destination Whirlpool' and there is no other connection between destination and source Whirlpools. In other words, entering Whirlpool A leads you to Whirlpool B, but entering Whirlpool B sends you to Whirlpool C instead of returning you to A. Likewise, Whirlpool C leads to Whirlpool D. In this way, Whirlpools exist in chains, sending you to a new Whirlpool each time until one sends you to a previous Whirlpool in the chain.
Practical example:
Map:

(Click for larger picture)
Known Whirlpools
Whirlpool A
Location: (-27,70)
Source: None known
Destination: Whirlpool B
Whirlpool B
Location: (-27,-80)
Source: Whirlpool A, Whirlpool D, Whirlpool L
Destination: Whirlpool C
Whirlpool C
Location: (1,-98)
Source: Whirlpool B
Destination: Whirlpool D
Whirlpool D
Location: (69,-15)
Source: Whirlpool C
Destination: Whirlpool B
Whirlpool E
Location: (-72,72)
Source: None known
Destination: Whirlpool G
Whirlpool F
Location: (-72,71)
Source: None known
Destination: Unknown
Whirlpool G
Location: (-119,-104)
Source: Whirlpool E
Destination: Whirlpool H
Whirlpool H
Location: (1,1)
Source: Whirlpool G
Destination: Whirlpool I
Whirlpool I
Location: (-98,7)
Source: Whirlpool H
Destination: Whirlpool J
Whirlpool J
Location: (26,10)
Source: Whirlpool I
Destination: Whirlpool K
Whirlpool K
Location: (28,55)
Source: Whirlpool J
Destination: Whirlpool L
Whirlpool L
Location: (30,70)
Source: Whirlpool K
Destination: Whirlpool B
Unknown Whirlpool (reported by borka)
Location: (-118, 74)
Source: Unknown
Destination: Unknown
Known chains:
(Brackets indicate a loop.)
A -> { B -> C -> D}
E -> G -> H -> I -> J -> K -> L -> { B -> C -> D }
If anybody has an unlisted Whirlpool near their home, could you try following and mapping the chain (preferably with screenshots so I can add it to the map I posted)? I think if we get these properly mapped out, travel would be MUCH faster.