Page 274 - Buck Tilton - Outward Bound Ropes, Knots, and Hitches 2 ed.

Reach through the right-hand loop and grasp the

left-hand loop.

Spanish Bowline: Step 4

Bring the left loop through the right loop.

On the downside, the ease of adjustment of the loops

means the final knot must be set very tight before use or
the loops could alter in size when the knot is weighted.

Since better methods of attaching people to ropes have
been developed, such as pre-sewn chairs, it is not
recommended to use the Spanish bowline as a chair except

in emergencies. Knotmaster Clifford Ashley referred to this
knot by the unwieldy name of a double splayed loop in the

bight.