Distant Twin Primes

The pair $3,5$ is special as it is the first prime pair to have difference of two. (Twin primes) After this, comes pair $5,7$. The distance between these two pairs is $2$ as it is calculated by subtracting the first member of each pair. Under $100$, the pair $59,61$ has the longest length from such previous pair $41,43$ with the distance of $18$.

Find longest distance of such prime pair, each member below one million, from such previous pair.