Boots of Bounding.

[Mike Reilly 321]

Does the increase from greater Boots of Bounding (+10 feet to speed) apply to all modes of speed as in burrow, fly, land and swim or just land?

[Siro]

I believe it’s only to land speed. Boots of Bounding only mentions the word ‘Speed’ with no specifying words, and on Page 463 of the Core rule book it mentions when no specifics are given to what type of speed, it is assumed to be land speed.

[beowulf99]

Siro is correct. Compare to Boots of Speed:

CRB PG. 606 "Boots of Speed" wrote:

These sleek red boots make your legs feel like

they’re bursting with energy. You gain a +5-foot
item bonus to your land Speed and to any
climb or swim Speeds you have.

Boots of Speed clearly modify your land, climb and swim speeds and states so clearly. That with the passage from 463 stating that when a rule refers to "Speed" with no qualifier that it is referring to you land speed, is pretty clear.