1		A city on Trans-Canada highway (anag. of 'tide machine') (8,3)
9		Cayman Trench is in this sea (9)
10		Italian province (sounds yellow- brown) (5)
11		People who provided ruling elite of what is now Rwanda and Burundi (5)
12		River outlets (9)
13		Siam formerly (8)
15		A warm ocean surge named "The Child" (2,4)
17		Snow transport (6)
19		The going cold and hard for this sort of sailing craft? (3,5)
22		Volcanic archipelago in Pacific (9)
23		A Nigerian province (5)
25		Tribe of ancient Britons of which Boudicca was queen (5)
26		Norwegian whirlpool (9)
27		They have the highest drop in S.Africa (6,5)

1		Martha holds a member of once- dominant people of SW India! (7)
2		Chief port, commercial centre of the United Arab Emirates (5)
3		American Indian people of the western plains (8)
4		Nomadic Arctic Russians (6)
5		African explorer who 'found' Livingstone (1,1,7)
6		Hinterland of S. France (3,4)
7		A native of northern Britain (4)
8		Traveller's permit (8)
13		Island south of Australia (8)
14		Electrical discharge between rain cloud and earth (9)
16		Perhaps the Ross one in Antarctica? (3,5)
18		The Khumbu icefall is one notorious feature of this peak (7)
20		Nicaraguan right-wing guerillas (7)
21		A duck-billed platypus, it's often pointed out, is one (6)
23		(one spelling of) a Swiss town (5)
24		A province of modern Greece (anag. of 'omen') (4)